supercomputing in plain english the tyranny of the storage hierarchy
DESCRIPTION
Supercomputing in Plain English The Tyranny of the Storage Hierarchy. PRESENTERNAME PRESENTERTITLE PRESENTERDEPARTMENT PRESENTERINSTITUTION DAY MONTH DATE YEAR. Your Logo Here. Slides by Henry Neeman, University of Oklahoma. Outline. Supercomputing in Plain English: Storage Hierarchy - PowerPoint PPT PresentationTRANSCRIPT
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Supercomputingin Plain English The Tyranny ofthe Storage HierarchyPRESENTERNAMEPRESENTERTITLEPRESENTERDEPARTMENTPRESENTERINSTITUTIONDAY MONTH DATE YEARYour Logo Here
Slides by Henry Neeman, University of Oklahoma
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
Your Logo Here
OutlineWhat is the storage hierarchy?RegistersCacheMain Memory (RAM)The Relationship Between RAM and CacheThe Importance of Being LocalHard DiskVirtual Memory*Supercomputing in Plain English: Storage HierarchyTue Feb 15 2011Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
Your Logo Here
The Storage HierarchyRegistersCache memoryMain memory (RAM)Hard diskRemovable media (CD, DVD etc)InternetSupercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*Fast, expensive, fewSlow, cheap, a lot
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
Your Logo Here
A LaptopIntel Core2 Duo SU9600 1.6 GHz w/3 MB L2 Cache4 GB 1066 MHz DDR3 SDRAM256 GB SSD Hard DriveDVD+RW/CD-RW Drive (8x)1 Gbps Ethernet AdapterSupercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*Dell Latitude Z600[4]
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
Your Logo Here
Storage Speed, Size, CostSupercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR** MFLOP/s: millions of floating point operations per second** 16 64-bit general purpose registers, 8 80-bit floating point registers, 16 128-bit floating point vector registers
LaptopRegisters(Intel Core2 Duo1.6 GHz)CacheMemory(L2)MainMemory(1066MHz DDR3 SDRAM)Hard Drive(SSD)Ethernet(1000 Mbps)DVD+R(16x)Phone Modem(56 Kbps)Speed(MB/sec)[peak]314,573[6](12,800 MFLOP/s*)27,276 [7]4500 [7]250 [9]12522 [10]0.007Size(MB)464 bytes**[11]34096256,000unlimitedunlimitedunlimitedCost($/MB)$285 [13]$0.03 [12]$0.002 [12]chargedper month(typically)$0.00005 [12]charged per month (typically)
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
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Registers[25]
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
Your Logo Here
What Are Registers?Registers are memory-like locations inside the Central Processing Unit that hold data that are being used right now in operations.Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*Arithmetic/Logic UnitControl UnitRegistersFetch Next InstructionAddSubMultDivAndOrNotIntegerFloating PointFetch DataStore DataIncrement Instruction PtrExecute InstructionCPUSupercomputing in Plain English: Storage HierarchyTue Feb 15 2011
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
Your Logo Here
How Registers Are UsedEvery arithmetic or logical operation has one or more operands and one result.Operands are contained in source registers.A black box of circuits performs the operation.The result goes into a destination register.Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*Example:addend in R0augend in R1ADDsum in R25712Register RiRegister RjRegister RkoperandoperandresultOperation circuitrySupercomputing in Plain English: Storage HierarchyTue Feb 15 2011
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
Your Logo Here
How Many Registers?Typically, a CPU has less than 8 KB (8192 bytes) of registers, usually split into registers for holding integer values and registers for holding floating point (real) values, plus a few special purpose registers.Examples:IBM POWER7 (found in IBM p-Series supercomputers): 226 64-bit integer registers and 348 128-bit merged vector/scalar registers (7376 bytes) [28]Intel Core2 Duo: 16 64-bit general purpose registers, 8 80-bit floating point registers, 16 128-bit floating point vector registers (464 bytes) [11]Intel Itanium2: 128 64-bit integer registers, 128 82-bit floating point registers (2304 bytes) [23]Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*Supercomputing in Plain English: Storage HierarchyTue Feb 15 2011
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
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Cache[4]
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
Your Logo Here
What is Cache?A special kind of memory where data reside that are about to be used or have just been used.Very fast => very expensive => very small (typically 100 to 10,000 times as expensive as RAM per byte)Data in cache can be loaded into or stored from registers at speeds comparable to the speed of performing computations.Data that are not in cache (but that are in Main Memory) take much longer to load or store.Cache is near the CPU: either inside the CPU or on the motherboard that the CPU sits on.Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*Supercomputing in Plain English: Storage HierarchyTue Feb 15 2011
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
Your Logo Here
From Cache to the CPUSupercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*Typically, data move between cache and the CPU at speeds relatively near to that of the CPU performing calculations.CPUCache27 GB/sec (6x RAM)[7]307 GB/sec[7]
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
Your Logo Here
Multiple Levels of CacheMost contemporary CPUs have more than one level of cache. For example:Intel Pentium4 EM64T (Yonah) [??]Level 1 caches: 32 KB instruction, 32 KB dataLevel 2 cache: 2048 KB unified (instruction+data)IBM POWER7 [28]Level 1 cache: 32 KB instruction, 32 KB data per coreLevel 2 cache: 256 KB unified per coreLevel 3 cache: 4096 KB unified per coreSupercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*Supercomputing in Plain English: Storage HierarchyTue Feb 15 2011
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
Your Logo Here
Why Multiple Levels of Cache?The lower the level of cache:the faster the cache can transfer data to the CPU;the smaller that level of cache is (faster => more expensive => smaller).Example: IBM POWER7 latency to the CPU [28]L1 cache: 1 cycle = 0.29 ns for 3.5 GHzL2 cache: 8.5 cycles = 2.43 ns for 3.5 GHz (average)L3 cache: 23.5 cycles = 5.53 ns for 3.5 GHz (local to core)RAM: 346 cycles = 98.86 ns for 3.5 GHz (1066 MHz RAM)Example: Intel Itanium2 latency to the CPU [19]L1 cache: 1 cycle = 1.0 ns for 1.0 GHzL2 cache: 5 cycles = 5.0 ns for 1.0 GHzL3 cache: 12-15 cycles = 12 15 ns for 1.0 GHzExample: Intel Pentium4 (Yonah)L1 cache: 3 cycles = 1.64 ns for a 1.83 GHz CPU = 12 calculationsL2 cache: 14 cycles = 7.65 ns for a 1.83 GHz CPU = 56 calculationsRAM: 48 cycles = 26.2 ns for a 1.83 GHz CPU = 192 calculations Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*Supercomputing in Plain English: Storage HierarchyTue Feb 15 2011
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
Your Logo Here
Cache & RAM LatenciesSupercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*Better[26]Supercomputing in Plain English: Storage HierarchyTue Feb 15 2011
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
MemLat
3
3.04
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3.02
3
3
3
3
3
3
3
3.02
3
3
3
3
3
3
3
3.02
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3.02
3
3
3
3
3.03
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3.02
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3.6
6.8
9.77
12.75
14.14
14.15
14.15
14.14
14.14
14.18
14.15
14.14
14.15
14.15
14.14
14.18
14.16
14.16
14.14
14.19
14.14
14.14
14.13
14.14
14.14
14.13
14.17
14.15
14.14
14.16
14.14
14.16
14.15
14.16
14.14
14.16
14.14
14.18
14.14
14.16
14.16
14.14
14.15
14.14
14.22
14.16
14.14
14.17
14.14
14.14
14.14
14.17
14.15
14.14
14.16
14.17
14.14
14.14
14.14
14.14
14.14
14.17
14.18
14.16
14.15
14.16
14.15
14.14
14.14
14.16
14.14
14.19
14.15
14.16
14.13
14.14
14.15
14.14
14.16
14.18
14.16
14.14
14.14
14.15
14.14
14.17
14.17
14.17
14.16
14.15
14.2
14.19
14.19
14.21
14.25
14.23
14.26
14.26
14.24
14.25
14.26
14.24
14.27
14.25
14.27
14.26
14.41
14.24
14.28
14.29
14.26
14.28
14.25
14.34
14.3
14.51
14.31
14.37
14.28
14.38
14.54
14.44
14.43
15.08
14.51
14.69
15.33
14.95
16.21
16.72
16.65
18.42
19.44
20.33
26.06
31.63
37.64
42.81
44.53
45.52
45.24
45.73
46.74
46.48
46.53
46.75
46.49
46.62
46.89
47.01
46.86
46.93
47.05
46.89
47.3
47.1
46.94
46.81
47.23
46.9
47.31
47.52
47.12
47.63
46.96
47.11
47.25
47.11
47.36
47.81
47.54
47.12
47.38
47.24
47.39
47.55
47.35
47.4
47.24
47.19
47.51
47.52
47.53
47.29
47.64
48.85
47.66
3 cycles
14 cycles
47 cycles
Memory Latency
Array Size (bytes)
Latency (clock cycles)
Cache & RAM Latency: Intel T2400 (1.83 GHz)
Sheet1
10243
10883.04
11523
12163
12803
13443
14083
14723
15363
16003
16643
17283
17923
18563
19203
19843
20483
21123
22403.02
23683
24963
26243
27523
28803
30083
31363
32643.02
33923
35203
36483
37763
39043
40323
41603
43523.02
45443
47363
49283
51203
53123
55043
56963
58883
60803
62723
65283
67843
70403
72963
75523
78083.02
80643
83203
86403
89603
92803.03
96003
99203
102403
105603
109443
113283
117123
120963
124803
129283
133763
138243
142723
147203
152323
157443
162563
167683
173443
179203
184963
191363.02
197763
204163
210563
217603
224643
231683
239363
247043
255363
263683
272003
280963
289923
299523
309123
319363
329603.6
340486.8
351369.77
3628812.75
3744014.14
3865614.15
3987214.15
4115214.14
4249614.14
4384014.18
4524814.15
4672014.14
4819214.15
4972814.15
5132814.14
5299214.18
5465614.16
5638414.16
5817614.14
6003214.19
6195214.14
6393614.14
6598414.13
6809614.14
7027214.14
7251214.13
7481614.17
7718414.15
7961614.14
8211214.16
8473614.14
8742414.16
9017614.15
9305614.16
9600014.14
9900814.16
10214414.14
10534414.18
10867214.14
11212814.16
11564814.16
11929614.14
12307214.15
12697614.14
13094414.22
13504014.16
13926414.14
14361614.17
14816014.14
15283214.14
15763214.14
16256014.17
16768014.15
17292814.14
17836814.16
18400014.17
18976014.14
19571214.14
20185614.14
20819214.14
21472014.14
22144014.17
22841614.18
23558414.16
24300814.15
25062414.16
25849614.15
26662414.14
27500814.14
28364814.16
29254414.14
30169614.19
31116814.15
32089614.16
33094414.13
34131214.14
35200014.15
36300814.14
37440014.16
38611214.18
39820814.16
41068814.14
42355214.14
43680014.15
45049614.14
46457614.17
47910414.17
49408014.17
50956814.16
52550414.15
54195214.2
55891214.19
57638414.19
59443214.21
61305614.25
63225614.23
65203214.26
67244814.26
69350414.24
71520014.25
73760014.26
76070414.24
78451214.27
80908814.25
83443214.27
86054414.26
88748814.41
91526414.24
94387214.28
97337614.29
100384014.26
103526414.28
106764814.25
110105614.34
113548814.3
117100814.51
120761614.31
124537614.37
128435214.28
132454414.38
136595214.54
140864014.44
145267214.43
149811215.08
154496014.51
159328014.69
164307215.33
169446414.95
174745616.21
180211216.72
185843216.65
191654418.42
197644819.44
203827220.33
210201626.06
216774431.63
223552037.64
230540842.81
237747244.53
245177645.52
252844845.24
260748845.73
268902446.74
277305646.48
285977646.53
294918446.75
304140846.49
313651246.62
323456046.89
333568047.01
343993646.86
354745646.93
365836847.05
377273646.89
389068847.3
401228847.1
413772846.94
426707246.81
440044847.23
453798446.9
467980847.31
482611247.52
497696047.12
513254447.63
529299246.96
545843247.11
562905647.25
580499247.11
598643247.36
617356847.81
636652847.54
656550447.12
677068847.38
698227247.24
720051247.39
742553647.55
765760047.35
789696047.4
814374447.24
839827247.19
866073647.51
893139247.52
921056047.53
949843247.29
979526447.64
1010137648.85
1041708847.66
rmma_intelt2400_memfwdlat_20070
RIGHTMARK MEMORY ANALYZER V3.72 TEST RESULTS
============================================
CPU ModelGenuine Intel(R) Core(TM) Duo (Yonah) 1828.7 MHz
L1 Cache Line Size64 bytes
L2 Cache Line Size128 bytes
Test TypeD-Cache Latency
Test StatusCompleted successfully
Selected Tests120
Set Size134217728 bytes
Memory Allocation1
Thread Lock0
Min Block Size1024 bytes
Max Block Size10485760 bytes
Stride Size64 bytes
Segments Count1
NOP Count0
Measurement Mode0
NOP Latency0
D-CACHE FORWARD READ LATENCY TEST
=================================
Size(bytes)Latency(cycles)Latency(ns)
102431.64
10883.041.66
115231.64
121631.64
128031.64
134431.64
140831.64
147231.64
153631.64
160031.64
166431.64
172831.64
179231.64
185631.64
192031.64
198431.64
204831.64
211231.64
22403.021.65
236831.64
249631.64
262431.64
275231.64
288031.64
300831.64
313631.64
32643.021.65
339231.64
352031.64
364831.64
377631.64
390431.64
403231.64
416031.64
43523.021.65
454431.64
473631.64
492831.64
512031.64
531231.64
550431.64
569631.64
588831.64
608031.64
627231.64
652831.64
678431.64
704031.64
729631.64
755231.64
78083.021.65
806431.64
832031.64
864031.64
896031.64
92803.031.65
960031.64
992031.64
1024031.64
1056031.64
1094431.64
1132831.64
1171231.64
1209631.64
1248031.64
1292831.64
1337631.64
1382431.64
1427231.64
1472031.64
1523231.64
1574431.64
1625631.64
1676831.64
1734431.64
1792031.64
1849631.64
191363.021.65
1977631.64
2041631.64
2105631.64
2176031.64
2246431.64
2316831.64
2393631.64
2470431.64
2553631.64
2636831.64
2720031.64
2809631.64
2899231.64
2995231.64
3091231.64
3193631.64
329603.61.97
340486.83.72
351369.775.34
3628812.756.97
3744014.147.73
3865614.157.74
3987214.157.74
4115214.147.73
4249614.147.73
4384014.187.76
4524814.157.74
4672014.147.73
4819214.157.74
4972814.157.74
5132814.147.73
5299214.187.76
5465614.167.75
5638414.167.74
5817614.147.73
6003214.197.76
6195214.147.73
6393614.147.73
6598414.137.73
6809614.147.73
7027214.147.73
7251214.137.73
7481614.177.75
7718414.157.74
7961614.147.73
8211214.167.74
8473614.147.73
8742414.167.74
9017614.157.74
9305614.167.74
9600014.147.73
9900814.167.74
10214414.147.73
10534414.187.76
10867214.147.73
11212814.167.75
11564814.167.75
11929614.147.73
12307214.157.74
12697614.147.73
13094414.227.77
13504014.167.74
13926414.147.73
14361614.177.75
14816014.147.73
15283214.147.73
15763214.147.73
16256014.177.75
16768014.157.74
17292814.147.73
17836814.167.74
18400014.177.75
18976014.147.73
19571214.147.73
20185614.147.73
20819214.147.73
21472014.147.73
22144014.177.75
22841614.187.75
23558414.167.74
24300814.157.74
25062414.167.74
25849614.157.74
26662414.147.73
27500814.147.73
28364814.167.74
29254414.147.73
30169614.197.76
31116814.157.74
32089614.167.74
33094414.137.73
34131214.147.73
35200014.157.74
36300814.147.73
37440014.167.74
38611214.187.76
39820814.167.74
41068814.147.73
42355214.147.73
43680014.157.74
45049614.147.73
46457614.177.75
47910414.177.75
49408014.177.75
50956814.167.75
52550414.157.74
54195214.27.76
55891214.197.76
57638414.197.76
59443214.217.77
61305614.257.79
63225614.237.78
65203214.267.8
67244814.267.8
69350414.247.79
71520014.257.79
73760014.267.8
76070414.247.79
78451214.277.81
80908814.257.79
83443214.277.8
86054414.267.8
88748814.417.88
91526414.247.79
94387214.287.81
97337614.297.82
100384014.267.8
103526414.287.81
106764814.257.79
110105614.347.84
113548814.37.82
117100814.517.93
120761614.317.82
124537614.377.86
128435214.287.81
132454414.387.87
136595214.547.95
140864014.447.89
145267214.437.89
149811215.088.25
154496014.517.94
159328014.698.03
164307215.338.38
169446414.958.18
174745616.218.86
180211216.729.14
185843216.659.1
191654418.4210.07
197644819.4410.63
203827220.3311.12
210201626.0614.25
216774431.6317.3
223552037.6420.58
230540842.8123.41
237747244.5324.35
245177645.5224.89
252844845.2424.74
260748845.7325.01
268902446.7425.56
277305646.4825.42
285977646.5325.45
294918446.7525.56
304140846.4925.42
313651246.6225.49
323456046.8925.64
333568047.0125.71
343993646.8625.62
354745646.9325.66
365836847.0525.73
377273646.8925.64
389068847.325.86
401228847.125.75
413772846.9425.67
426707246.8125.6
440044847.2325.83
453798446.925.64
467980847.3125.87
482611247.5225.99
497696047.1225.77
513254447.6326.05
529299246.9625.68
545843247.1125.76
562905647.2525.84
580499247.1125.76
598643247.3625.9
617356847.8126.14
636652847.5426
656550447.1225.77
677068847.3825.91
698227247.2425.83
720051247.3925.91
742553647.5526
765760047.3525.89
789696047.425.92
814374447.2425.83
839827247.1925.81
866073647.5125.98
893139247.5225.98
921056047.5325.99
949843247.2925.86
979526447.6426.05
1010137648.8526.71
1041708847.6626.06
D-CACHE BACKWARD READ LATENCY TEST
==================================
Size(bytes)Latency(cycles)Latency(ns)
102431.64
10883.021.65
115231.64
121631.64
128031.64
134431.64
140831.64
147231.64
153631.64
160031.64
166431.64
172831.64
179231.64
185631.64
192031.64
198431.64
204831.64
211231.64
224031.64
236831.64
249631.64
262431.64
275231.64
288031.64
300831.64
313631.64
326431.64
339231.64
352031.64
364831.64
377631.64
390431.64
403231.64
416031.64
435231.64
454431.64
473631.64
492831.64
512031.64
531231.64
550431.64
569631.64
588831.64
608031.64
627231.64
652831.64
678431.64
704031.64
729631.64
755231.64
780831.64
806431.64
832031.64
864031.64
896031.64
928031.64
960031.64
992031.64
1024031.64
1056031.64
1094431.64
1132831.64
1171231.64
1209631.64
1248031.64
1292831.64
1337631.64
1382431.64
1427231.64
1472031.64
1523231.64
1574431.64
1625631.64
1676831.64
1734431.64
1792031.64
1849631.64
1913631.64
1977631.64
2041631.64
2105631.64
2176031.64
2246431.64
2316831.64
2393631.64
2470431.64
2553631.64
2636831.64
2720031.64
2809631.64
2899231.64
2995231.64
3091231.64
3193631.64
329603.61.97
340486.813.72
351369.745.33
3628812.756.97
3744014.137.73
3865614.197.76
3987214.167.74
4115214.147.73
4249614.147.73
4384014.147.73
4524814.167.74
4672014.157.74
4819214.167.74
4972814.157.74
5132814.147.73
5299214.167.74
5465614.147.73
5638414.137.73
5817614.147.73
6003214.157.74
6195214.167.74
6393614.187.75
6598414.147.73
6809614.137.73
7027214.157.74
7251214.147.73
7481614.167.74
7718414.167.75
7961614.157.74
8211214.147.73
8473614.147.73
8742414.167.74
9017614.147.73
9305614.137.73
9600014.147.73
9900814.147.73
10214414.157.74
10534414.197.76
10867214.137.73
11212814.157.74
11564814.157.74
11929614.137.73
12307214.167.74
12697614.147.73
13094414.157.74
13504014.27.77
13926414.157.74
14361614.167.75
14816014.147.73
15283214.137.73
15763214.147.73
16256014.157.74
16768014.157.74
17292814.167.74
17836814.147.73
18400014.147.73
18976014.157.74
19571214.187.75
20185614.157.74
20819214.147.73
21472014.167.74
22144014.167.74
22841614.167.74
23558414.147.73
24300814.147.73
25062414.137.73
25849614.197.76
26662414.167.74
27500814.147.73
28364814.157.74
29254414.167.74
30169614.167.74
31116814.157.74
32089614.177.75
33094414.177.75
34131214.157.74
35200014.147.73
36300814.187.75
37440014.157.74
38611214.157.74
39820814.147.73
41068814.187.76
42355214.177.75
43680014.147.73
45049614.147.73
46457614.147.73
47910414.147.73
49408014.157.74
50956814.157.74
52550414.167.74
54195214.197.76
55891214.187.76
57638414.217.77
59443214.37.82
61305614.327.83
63225614.277.8
65203214.287.81
67244814.297.81
69350414.337.84
71520014.257.79
73760014.617.99
76070414.337.84
78451214.387.86
80908814.337.84
83443214.357.85
86054414.437.89
88748814.367.85
91526414.267.8
94387214.397.87
97337614.287.81
100384014.317.82
103526414.387.87
106764814.347.84
110105614.437.89
113548814.417.88
117100814.517.93
120761614.347.84
124537614.47.87
128435214.397.87
132454414.517.94
136595214.357.85
140864014.668.02
145267215.348.39
149811214.778.08
154496016.59.02
159328015.198.31
164307215.788.63
169446415.278.35
174745615.28.31
180211215.788.63
185843217.589.61
191654418.5510.14
197644820.0510.97
203827221.611.81
210201626.2514.36
216774432.2617.64
223552039.621.65
230540842.9623.49
237747245.6224.95
245177645.9725.14
252844846.6125.49
260748846.8225.6
268902446.1825.25
277305647.2125.82
285977646.8725.63
294918446.9525.67
304140847.9326.21
313651247.2425.83
323456046.6425.5
333568047.2325.82
343993647.3425.89
354745646.9725.68
365836847.2825.86
377273647.4425.94
389068847.6426.05
401228846.9825.69
413772847.5225.99
426707247.4225.93
440044847.3725.9
453798447.4925.97
467980847.7126.09
482611247.9926.24
497696047.6726.07
513254447.425.92
529299247.6626.06
545843247.8526.17
562905647.6826.08
58049924826.25
598643247.4925.97
617356847.726.08
636652847.6326.05
656550448.0726.29
677068847.4925.97
698227247.7126.09
720051248.2626.39
742553647.3425.89
765760047.2825.86
789696047.6426.05
814374447.8826.18
839827248.0526.28
866073647.7926.13
893139247.8526.17
921056047.626.03
949843247.4125.92
979526447.8626.17
1010137648.8926.73
1041708847.4625.95
D-CACHE RANDOM READ LATENCY TEST
================================
Size(bytes)Latency(cycles)Latency(ns)
10243.031.65
108831.64
115231.64
121631.64
128031.64
13443.031.65
140831.64
147231.64
153631.64
160031.64
166431.64
172831.64
179231.64
185631.64
192031.64
19843.011.65
204831.64
211231.64
224031.64
236831.64
249631.64
26243.031.65
275231.64
288031.64
300831.64
31363.021.65
326431.64
339231.64
352031.64
364831.64
37763.021.65
390431.64
403231.64
416031.64
435231.64
45443.031.65
473631.64
492831.64
512031.64
531231.64
55043.021.65
569631.64
588831.64
608031.64
627231.64
65283.021.65
678431.64
704031.64
729631.64
755231.64
78083.021.65
806431.64
832031.64
864031.64
896031.64
928031.64
960031.64
992031.64
1024031.64
105603.021.65
1094431.64
1132831.64
1171231.64
1209631.64
1248031.64
1292831.64
1337631.64
1382431.64
1427231.64
147203.031.65
1523231.64
1574431.64
1625631.64
1676831.64
173443.031.66
1792031.64
1849631.64
1913631.64
197763.021.65
2041631.64
2105631.64
2176031.64
2246431.64
2316831.64
239363.021.65
2470431.64
2553631.64
2636831.64
272003.031.66
2809631.64
2899231.64
2995231.64
3091231.64
319363.031.66
329603.61.97
340486.653.64
351369.575.24
3628812.556.86
3744013.987.65
3865614.017.66
3987214.157.74
4115214.177.75
4249614.217.77
4384014.147.73
4524814.167.74
4672014.147.73
4819214.157.74
4972814.147.73
5132814.147.73
5299214.177.75
5465614.157.74
5638414.187.75
5817614.157.74
6003214.137.73
6195214.167.74
6393614.157.74
6598414.137.73
6809614.187.75
7027214.177.75
7251214.167.74
7481614.177.75
7718414.167.74
7961614.167.74
8211214.167.74
8473614.157.74
8742414.147.73
9017614.167.74
9305614.147.73
9600014.137.73
9900814.167.75
10214414.157.74
10534414.137.73
10867214.157.74
11212814.157.74
11564814.137.73
11929614.147.73
12307214.147.73
12697614.147.73
13094414.187.75
13504014.147.73
13926414.147.73
14361614.167.74
14816014.167.74
15283214.147.73
15763214.157.74
16256014.147.73
16768014.147.73
17292814.157.74
17836814.157.74
18400014.137.73
18976014.167.74
19571214.167.74
20185614.147.73
20819214.147.73
21472014.157.74
22144014.157.74
22841614.167.75
23558414.157.74
24300814.157.74
25062414.137.73
25849614.147.73
26662414.157.73
27500814.147.73
28364814.177.75
29254414.187.76
30169614.147.73
31116814.167.75
32089614.167.74
33094414.167.74
34131214.167.75
35200014.167.74
36300814.157.74
37440014.187.75
38611214.157.74
39820814.147.73
41068814.157.74
42355214.147.73
43680014.177.75
45049614.157.74
46457614.177.75
47910414.267.8
49408014.167.74
50956814.157.74
52550414.197.76
54195214.367.85
55891214.487.92
57638414.67.98
59443214.748.06
61305614.868.12
63225615.038.22
65203215.18.25
67244815.218.32
69350415.278.35
71520015.378.4
73760015.488.46
76070415.648.55
78451215.698.58
80908815.778.62
83443215.958.72
86054415.958.72
88748816.048.77
91526416.18.81
94387216.258.88
97337616.318.92
100384016.378.95
103526416.519.03
106764816.839.21
110105616.659.1
113548816.889.23
117100816.799.18
120761616.849.21
124537616.959.27
1284352179.3
132454417.159.38
136595217.319.47
140864017.49.52
145267217.549.59
149811217.439.53
154496017.69.62
159328018.4110.07
164307219.0810.44
169446418.3510.03
174745619.0710.43
180211219.9110.89
185843221.9812.02
191654423.4112.8
197644836.4619.93
203827242.323.13
210201649.3426.98
216774475.0541.04
223552094.0151.41
2305408101.1755.32
2377472108.3159.23
2451776111.6261.04
2528448114.4262.57
2607488116.7263.83
2689024116.0363.45
2773056116.7363.83
2859776117.3464.16
2949184118.0364.54
3041408120.8266.07
3136512121.8866.65
3234560124.1767.9
3335680127.0569.47
3439936127.3669.64
3547456129.8771.02
3658368131.2571.77
3772736136.5474.67
3890688135.9674.35
4012288140.1476.63
413772814177.1
4267072142.6778.01
4400448145.4779.55
4537984146.5480.13
4679808149.4881.74
4826112151.6682.93
4976960151.682.9
5132544155.9185.26
5292992156.2785.45
5458432157.4286.08
5629056158.6586.76
5804992159.0386.96
5986432161.0788.08
6173568162.0688.62
6366528163.589.4
6565504165.1490.3
6770688167.2891.47
6982272167.9991.86
7200512169.9592.93
7425536170.8993.45
7657600171.9894.04
7896960173.1394.67
8143744174.5195.43
8398272175.3895.9
8660736176.1496.32
8931392177.4697.04
9210560178.8697.81
9498432179.698.21
9795264180.4198.65
10101376179.5398.17
10417088180.2598.56
D-CACHE PSEUDO-RANDOM READ LATENCY TEST
=======================================
Size(bytes)Latency(cycles)Latency(ns)
10243.021.65
108831.64
115231.64
121631.64
12803.031.65
134431.64
140831.64
147231.64
153631.64
16003.031.65
166431.64
172831.64
179231.64
18563.031.65
192031.64
198431.64
204831.64
211231.64
224031.64
236831.64
249631.64
262431.64
27523.031.65
288031.64
300831.64
313631.64
32643.021.65
339231.64
352031.64
364831.64
377631.64
39043.031.66
403231.64
416031.64
435231.64
454431.64
473631.64
492831.64
512031.64
53123.031.66
550431.64
569631.64
588831.64
60803.021.65
627231.64
652831.64
678431.64
70403.021.65
729631.64
755231.64
780831.64
806431.64
83203.021.65
864031.64
896031.64
928031.64
96003.031.65
992031.64
1024031.64
1056031.64
109443.021.65
1132831.64
1171231.64
1209631.64
1248031.64
1292831.64
1337631.64
1382431.64
1427231.64
1472031.64
1523231.64
1574431.64
1625631.64
167683.031.65
1734431.64
1792031.64
1849631.64
1913631.64
1977631.64
2041631.64
2105631.64
217603.031.66
2246431.64
2316831.64
2393631.64
2470431.64
255363.031.66
2636831.64
2720031.64
2809631.64
289923.021.65
2995231.64
3091231.64
3193631.64
329603.611.97
340486.83.72
351369.85.36
3628812.756.97
3744014.167.74
3865614.187.75
3987214.177.75
4115214.167.74
4249614.157.74
4384014.157.74
4524814.167.74
4672014.157.74
4819214.147.73
4972814.157.74
5132814.147.73
5299214.177.75
5465614.197.76
5638414.197.76
5817614.157.74
6003214.177.75
6195214.167.74
6393614.167.75
6598414.187.75
6809614.167.74
7027214.167.74
7251214.217.77
7481614.157.74
7718414.187.75
7961614.217.77
8211214.187.75
8473614.197.76
8742414.217.77
9017614.137.73
9305614.177.75
9600014.167.74
9900814.197.76
10214414.147.73
10534414.157.74
10867214.167.74
11212814.217.77
11564814.167.74
11929614.167.75
12307214.157.74
12697614.167.74
13094414.167.75
13504014.157.74
13926414.187.75
14361614.177.75
14816014.167.74
15283214.177.75
15763214.217.77
16256014.187.75
16768014.197.76
17292814.177.75
17836814.187.75
18400014.27.77
18976014.187.76
19571214.187.75
20185614.157.74
20819214.187.76
21472014.167.74
22144014.177.75
22841614.177.75
23558414.197.76
24300814.187.76
25062414.167.74
25849614.187.75
26662414.177.75
27500814.197.76
28364814.167.75
29254414.217.77
30169614.187.75
31116814.177.75
32089614.187.76
33094414.187.75
34131214.157.74
35200014.197.76
36300814.177.75
37440014.177.75
38611214.177.75
39820814.167.75
41068814.27.77
42355214.177.75
43680014.187.76
45049614.187.76
46457614.167.74
47910414.167.74
49408014.187.75
50956814.157.74
52550414.177.75
54195214.187.76
55891214.237.78
57638414.227.78
59443214.237.78
61305614.267.8
63225614.277.8
65203214.297.82
67244814.297.82
69350414.267.8
71520014.277.8
73760014.337.84
76070414.317.83
78451214.357.84
80908814.297.81
83443214.297.81
86054414.337.84
88748814.297.81
91526414.277.81
94387214.277.8
97337614.437.89
100384014.317.82
103526414.277.8
106764814.277.8
110105614.347.84
113548814.337.83
117100814.327.83
120761614.437.89
124537614.347.84
128435214.37.82
132454414.357.85
136595214.698.03
140864014.397.87
145267214.387.86
149811214.638
154496014.597.98
159328014.78.04
164307214.968.18
169446415.238.33
174745615.218.31
180211216.058.78
185843218.219.96
191654419.4610.64
197644823.3612.77
203827229.7916.29
210201633.9618.57
216774461.8633.82
223552077.5542.41
230540889.1448.74
237747294.651.73
245177694.9251.9
252844895.4952.21
260748896.8252.95
268902497.5753.36
277305697.4453.28
285977698.153.65
294918498.2353.71
304140898.2653.73
313651298.3953.8
323456098.6753.95
333568099.254.25
343993699.1454.21
354745698.9354.1
365836899.1854.23
377273699.2954.3
389068899.8654.6
401228899.4154.36
413772899.3154.31
426707299.7254.53
440044899.6854.51
453798499.3654.33
467980899.1454.21
482611299.5554.44
497696099.6754.5
513254499.3154.31
529299299.2154.25
545843299.4854.4
5629056100.1254.75
580499299.4354.37
598643299.854.58
617356899.4354.37
636652899.5154.42
656550499.3954.35
677068899.6754.5
698227299.4954.4
720051299.254.25
742553699.9854.67
765760099.3854.34
789696099.8654.61
814374499.8254.59
839827299.5854.45
8660736100.2454.82
8931392100.2954.84
9210560100.1554.76
9498432100.0254.69
979526499.8754.61
10101376100.4554.93
10417088100.1654.77
-
Main Memory[13]
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
Your Logo Here
What is Main Memory?Where data reside for a program that is currently runningSometimes called RAM (Random Access Memory): you can load from or store into any main memory location at any timeSometimes called core (from magnetic cores that some memories used, many years ago)Much slower => much cheaper => much bigger
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*Supercomputing in Plain English: Storage HierarchyTue Feb 15 2011
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
Your Logo Here
What Main Memory Looks LikeSupercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*012345678910536,870,911You can think of main memory as a big long 1D array of bytes.
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
-
The Relationship BetweenMain Memory & Cache
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
Your Logo Here
RAM is SlowSupercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*CPU307 GB/sec[6]4.4 GB/sec[7] (1.4%)BottleneckThe speed of data transferbetween Main Memory and theCPU is much slower than thespeed of calculating, so the CPUspends most of its time waitingfor data to come in or go out.
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
Your Logo Here
Why Have Cache?Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*CPUCache is much closer to the speedof the CPU, so the CPU doesnthave to wait nearly as long forstuff thats already in cache:it can do moreoperations per second!4.4 GB/sec[7] (1%)27 GB/sec (9%)[7]
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
Your Logo Here
Cache & RAM BandwidthsSupercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*Better[26]Supercomputing in Plain English: Storage HierarchyTue Feb 15 2011
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
Cache & RAM Bandwidth
14247.1814210.38
14386.7714180.11
14435.2214165.56
14457.6514182.99
14466.7114185.19
14476.2814174.7
14485.114198.12
14498.3414169.3
14483.5114182.34
14498.0114181.44
14498.7414202.71
14508.1114139.8
14507.5814181.87
14513.114194.58
14500.0414158.15
14513.5114186.06
14516.7714194.11
14513.8114155.92
14509.3614188.26
14516.2714178.59
14518.3114180.03
14508.4714184.54
14511.1814191.08
14519.2214189.59
14515.1614190.39
14509.7714188.29
14507.1114183.02
14515.5914192.23
14508.5314186.89
14518.0514168.5
14203.114024.38
14196.0914044.27
11519.7211755.13
8650.69079.46
7843.678249.91
7844.668255.21
7848.98237.1
7856.328259.32
7841.438262.92
7856.788259.96
7847.188246.82
7853.258255.26
7848.058246.77
7838.118250.94
7853.978243.19
7853.788261.14
7849.578248.73
7854.248260.4
7853.68231.9
7847.248253.33
7857.718177.5
7861.58247.45
7857.648257.7
7860.948253.15
7837.248255.14
7853.538243.88
7850.788254.16
7860.198240.45
7862.658235.63
7860.98257.26
7865.088261.5
7865.778247.68
7858.748247.77
7857.178205.32
7863.588238.6
7861.458249.15
7863.958235.33
7865.718255.3
7855.078243.98
7868.618258.39
7853.498236.09
7860.658210.25
7859.688254
7867.578253.59
7867.228259.73
7851.688246.81
7866.578256.6
7861.838241.05
7836.388247.16
7867.898243.68
7867.728261.13
7865.678240.21
7867.298224.45
7860.898257.53
7866.978248.44
7857.758256.1
7864.658246.46
7866.928256.44
7864.358240.2
7868.738256.85
7857.198257.51
7850.648260.73
7865.468251.95
7858.488259.42
7860.478259.32
7864.988261.1
7872.738245.37
7867.558259.95
7861.678224.83
7857.068237.93
7860.468199.36
7849.258257.12
7870.998189.58
7865.28215.24
7862.68237.23
7852.58248.6
7852.088245.84
7866.578258.02
7856.98250.85
7853.578230.01
7840.18190.94
7820.758177.06
7806.388128.59
7777.878140.93
7779.198088.6
7778.958101.97
7774.668060.33
7752.698101
7770.038094.78
7776.568053.9
7758.878101.12
7772.358068.58
7772.168095.8
7763.728074.29
7773.928083.87
7777.268070.48
7771.848099.73
7719.598075.81
7768.828096.28
7775.098056.91
7771.168086.48
7755.968096.3
7760.128078.07
7759.88068.23
7631.788054.83
7618.28047.63
7732.027956.87
7655.858042.72
7725.87996.28
7714.618056.72
7515.067858
7624.127895.5
7637.937741.66
7636.537945.8
7341.237853.66
7515.287781.19
7237.047747.09
7461.547250.46
7256.97378.14
6696.777106.15
6737.496343.97
6547.116249.16
5991.115018.53
5836.484482.27
4959.793418.65
4657.392772.85
4336.382547.29
3988.922312.31
40162166.92
3931.62095.44
3810.271995.24
3820.211954.69
3848.281899.1
3799.91840.8
3772.091796.24
3765.111742.41
3750.181723.53
3743.71703.83
3682.081668.98
3664.431642.6
3704.841618.6
3619.751592.33
3603.381585.18
3629.121563.99
3661.951535.88
3667.141531.17
3665.121524.09
3658.151495.36
3603.331507.28
3649.911488.69
3607.021469.99
3496.531455.48
3640.171464.54
3644.711452.88
3596.211437.13
3635.891446.52
3537.251427.81
3623.651422.92
3597.521420.96
3601.781442.96
3568.331423.41
3584.591443.29
3608.711427.09
3626.661400.76
3584.251398.39
3566.341386.02
3616.271407.95
3500.151398.48
32 KB (L1 cache size)
2 MB (L2 cache size)
7.7 GB/sec
14.2 GB/sec
3.5 GB/sec
1.4 GB/sec
Read BW
Write BW
Array Size (bytes)
Bandwidth (MB/sec)
Cache & RAM Bandwidth: Intel T2400 (1.83 GHz)
Sheet1
102414247.1814210.38
204814386.7714180.11
307214435.2214165.56
409614457.6514182.99
512014466.7114185.19
614414476.2814174.7
716814485.114198.12
819214498.3414169.3
921614483.5114182.34
1024014498.0114181.44
1126414498.7414202.71
1228814508.1114139.8
1331214507.5814181.87
1433614513.114194.58
1536014500.0414158.15
1638414513.5114186.06
1740814516.7714194.11
1843214513.8114155.92
1945614509.3614188.26
2048014516.2714178.59
2150414518.3114180.03
2252814508.4714184.54
2355214511.1814191.08
2457614519.2214189.59
2560014515.1614190.39
2662414509.7714188.29
2764814507.1114183.02
2867214515.5914192.23
2969614508.5314186.89
3072014518.0514168.5
3174414203.114024.38
3276814196.0914044.27
3379211519.7211755.13
358408650.69079.46
378887843.678249.91
399367844.668255.21
419847848.98237.1
440327856.328259.32
460807841.438262.92
481287856.788259.96
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522247853.258255.26
542727848.058246.77
563207838.118250.94
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624647849.578248.73
645127854.248260.4
665607853.68231.9
696327847.248253.33
727047857.718177.5
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788487857.648257.7
819207860.948253.15
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1044487865.088261.5
1085447865.778247.68
1126407858.748247.77
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1208327863.588238.6
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1996807867.898243.68
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2355207866.978248.44
2437127857.758256.1
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2775047868.738256.85
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3266567860.478259.32
3368967864.988261.1
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3829767857.068237.93
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7710727772.358068.58
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8212487763.728074.29
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9605127768.828096.28
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10895367760.128078.07
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13557767714.618056.72
13987847515.067858
14428167624.127895.5
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17387527461.547250.46
17940487256.97378.14
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19691526547.116249.16
20316165991.115018.53
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21606404959.793418.65
22282244657.392772.85
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23705603988.922312.31
244531240162166.92
25221123931.62095.44
26009603810.271995.24
26828803820.211954.69
27668483848.281899.1
28538883799.91840.8
29440003772.091796.24
30361603765.111742.41
31313923750.181723.53
32296963743.71703.83
33310723682.081668.98
34355203664.431642.6
35430403704.841618.6
36546563619.751592.33
37693443603.381585.18
38881283629.121563.99
40099843661.951535.88
41359363667.141531.17
42659843665.121524.09
44001283658.151495.36
45383683603.331507.28
46807043649.911488.69
48271363607.021469.99
49786883496.531455.48
51343363640.171464.54
52951043644.711452.88
54609923596.211437.13
56320003635.891446.52
58081283537.251427.81
59904003623.651422.92
61777923597.521420.96
63713283601.781442.96
65710083568.331423.41
67768323584.591443.29
69888003608.711427.09
72079363626.661400.76
74332163584.251398.39
76656643566.341386.02
79052803616.271407.95
81530883500.151398.48
rmma_intelt2400_membw_20070904
RIGHTMARK MEMORY ANALYZER V3.72 TEST RESULTS
============================================
CPU ModelGenuine Intel(R) Core(TM) Duo (Yonah) 1828.7 MHz
L1 Cache Line Size64 bytes
L2 Cache Line Size128 bytes
Test TypeMemory Bandwidth
Test StatusCompleted successfully
Selected Tests7
Set Size134217728 bytes
Memory Allocation1
Thread Lock0
Min Block Size1024 bytes
Max Block Size8388608 bytes
CPU Register Usage0
Read Prefetch Type0
Prefetch Distance0 bytes
Block Prefetch Size1024 bytes
Stride Size64 bytes
Non-Temporal Store0
Copy-to-Self Mode0
MEMORY READ BANDWIDTH TEST
==========================
Size(bytes)Bandwidth(bytes/cycle)Bandwidth(MB/s)
10247.7914247.18
20487.8714386.77
30727.8914435.22
40967.9114457.65
51207.9114466.71
61447.9214476.28
71687.9214485.1
81927.9314498.34
92167.9214483.51
102407.9314498.01
112647.9314498.74
122887.9314508.11
133127.9314507.58
143367.9414513.1
153607.9314500.04
163847.9414513.51
174087.9414516.77
184327.9414513.81
194567.9314509.36
204807.9414516.27
215047.9414518.31
225287.9314508.47
235527.9414511.18
245767.9414519.22
256007.9414515.16
266247.9314509.77
276487.9314507.11
286727.9414515.59
296967.9314508.53
307207.9414518.05
317447.7714203.1
327687.7614196.09
337926.311519.72
358404.738650.6
378884.297843.67
399364.297844.66
419844.297848.9
440324.37856.32
460804.297841.43
481284.37856.78
501764.297847.18
522244.297853.25
542724.297848.05
563204.297838.11
583684.297853.97
604164.297853.78
624644.297849.57
645124.297854.24
665604.297853.6
696324.297847.24
727044.37857.71
757764.37861.5
788484.37857.64
819204.37860.94
849924.297837.24
880644.297853.53
911364.297850.78
942084.37860.19
972804.37862.65
1003524.37860.9
1044484.37865.08
1085444.37865.77
1126404.37858.74
1167364.37857.17
1208324.37863.58
1249284.37861.45
1290244.37863.95
1331204.37865.71
1382404.37855.07
1433604.37868.61
1484804.297853.49
1536004.37860.65
1587204.37859.68
1638404.37867.57
1689604.37867.22
1751044.297851.68
1812484.37866.57
1873924.37861.83
1935364.297836.38
1996804.37867.89
2068484.37867.72
2140164.37865.67
2211844.37867.29
2283524.37860.89
2355204.37866.97
2437124.37857.75
2519044.37864.65
2600964.37866.92
2682884.37864.35
2775044.37868.73
2867204.37857.19
2959364.297850.64
3061764.37865.46
3164164.37858.48
3266564.37860.47
3368964.37864.98
3481604.37872.73
3594244.37867.55
3706884.37861.67
3829764.37857.06
3952644.37860.46
4085764.297849.25
4218884.37870.99
4352004.37865.2
4495364.37862.6
4638724.297852.5
4792324.297852.08
4945924.37866.57
5109764.37856.9
5273604.297853.57
5447684.297840.1
5621764.287820.75
5806084.277806.38
5990404.257777.87
6184964.257779.19
6379524.257778.95
6584324.257774.66
6799364.247752.69
7014404.257770.03
7239684.257776.56
7475204.247758.87
7710724.257772.35
7956484.257772.16
8212484.257763.72
8478724.257773.92
8744964.257777.26
9021444.257771.84
9308164.227719.59
9605124.257768.82
9912324.257775.09
10229764.257771.16
10557444.247755.96
10895364.247760.12
11243524.247759.8
11601924.177631.78
11970564.177618.2
12349444.237732.02
12738564.197655.85
13137924.227725.8
13557764.227714.61
13987844.117515.06
14428164.177624.12
14888964.187637.93
15360004.187636.53
15841284.017341.23
16343044.117515.28
16855043.967237.04
17387524.087461.54
17940483.977256.9
18503683.666696.77
19087363.686737.49
19691523.586547.11
20316163.285991.11
20951043.195836.48
21606402.714959.79
22282242.554657.39
22978562.374336.38
23705602.183988.92
24453122.24016
25221122.153931.6
26009602.083810.27
26828802.093820.21
27668482.13848.28
28538882.083799.9
29440002.063772.09
30361602.063765.11
31313922.053750.18
32296962.053743.7
33310722.013682.08
343552023664.43
35430402.033704.84
36546561.983619.75
37693441.973603.38
38881281.983629.12
400998423661.95
41359362.013667.14
426598423665.12
440012823658.15
45383681.973603.33
468070423649.91
48271361.973607.02
49786881.913496.53
51343361.993640.17
52951041.993644.71
54609921.973596.21
56320001.993635.89
58081281.933537.25
59904001.983623.65
61777921.973597.52
63713281.973601.78
65710081.953568.33
67768321.963584.59
69888001.973608.71
72079361.983626.66
74332161.963584.25
76656641.953566.34
79052801.983616.27
81530881.913500.15
MAXIMAL READ BANDWIDTH
245767.9414519.22
MEMORY WRITE BANDWIDTH TEST
===========================
Size(bytes)Bandwidth(bytes/cycle)Bandwidth(MB/s)
10247.7714210.38
20487.7514180.11
30727.7514165.56
40967.7614182.99
51207.7614185.19
61447.7514174.7
71687.7614198.12
81927.7514169.3
92167.7614182.34
102407.7514181.44
112647.7714202.71
122887.7314139.8
133127.7514181.87
143367.7614194.58
153607.7414158.15
163847.7614186.06
174087.7614194.11
184327.7414155.92
194567.7614188.26
204807.7514178.59
215047.7514180.03
225287.7614184.54
235527.7614191.08
245767.7614189.59
256007.7614190.39
266247.7614188.29
276487.7614183.02
286727.7614192.23
296967.7614186.89
307207.7514168.5
317447.6714024.38
327687.6814044.27
337926.4311755.13
358404.969079.46
378884.518249.91
399364.518255.21
419844.58237.1
440324.528259.32
460804.528262.92
481284.528259.96
501764.518246.82
522244.518255.26
542724.518246.77
563204.518250.94
583684.518243.19
604164.528261.14
624644.518248.73
645124.528260.4
665604.58231.9
696324.518253.33
727044.478177.5
757764.518247.45
788484.528257.7
819204.518253.15
849924.518255.14
880644.518243.88
911364.518254.16
942084.518240.45
972804.58235.63
1003524.528257.26
1044484.528261.5
1085444.518247.68
1126404.518247.77
1167364.498205.32
1208324.518238.6
1249284.518249.15
1290244.58235.33
1331204.518255.3
1382404.518243.98
1433604.528258.39
1484804.58236.09
1536004.498210.25
1587204.518254
1638404.518253.59
1689604.528259.73
1751044.518246.81
1812484.518256.6
1873924.518241.05
1935364.518247.16
1996804.518243.68
2068484.528261.13
2140164.518240.21
2211844.58224.45
2283524.528257.53
2355204.518248.44
2437124.518256.1
2519044.518246.46
2600964.518256.44
2682884.518240.2
2775044.528256.85
2867204.528257.51
2959364.528260.73
3061764.518251.95
3164164.528259.42
3266564.528259.32
3368964.528261.1
3481604.518245.37
3594244.528259.95
3706884.58224.83
3829764.58237.93
3952644.488199.36
4085764.528257.12
4218884.488189.58
4352004.498215.24
4495364.58237.23
4638724.518248.6
4792324.518245.84
4945924.528258.02
5109764.518250.85
5273604.58230.01
5447684.488190.94
5621764.478177.06
5806084.448128.59
5990404.458140.93
6184964.428088.6
6379524.438101.97
6584324.418060.33
6799364.438101
7014404.438094.78
7239684.48053.9
7475204.438101.12
7710724.418068.58
7956484.438095.8
8212484.428074.29
8478724.428083.87
8744964.418070.48
9021444.438099.73
9308164.428075.81
9605124.438096.28
9912324.418056.91
10229764.428086.48
10557444.438096.3
10895364.428078.07
11243524.418068.23
11601924.48054.83
11970564.48047.63
12349444.357956.87
12738564.48042.72
13137924.377996.28
13557764.418056.72
13987844.37858
14428164.327895.5
14888964.237741.66
15360004.347945.8
15841284.297853.66
16343044.257781.19
16855044.247747.09
17387523.967250.46
17940484.037378.14
18503683.897106.15
19087363.476343.97
19691523.426249.16
20316162.745018.53
20951042.454482.27
21606401.873418.65
22282241.522772.85
22978561.392547.29
23705601.262312.31
24453121.182166.92
25221121.152095.44
26009601.091995.24
26828801.071954.69
27668481.041899.1
28538881.011840.8
29440000.981796.24
30361600.951742.41
31313920.941723.53
32296960.931703.83
33310720.911668.98
34355200.91642.6
35430400.891618.6
36546560.871592.33
37693440.871585.18
38881280.861563.99
40099840.841535.88
41359360.841531.17
42659840.831524.09
44001280.821495.36
45383680.821507.28
46807040.811488.69
48271360.81469.99
49786880.81455.48
51343360.81464.54
52951040.791452.88
54609920.791437.13
56320000.791446.52
58081280.781427.81
59904000.781422.92
61777920.781420.96
63713280.791442.96
65710080.781423.41
67768320.791443.29
69888000.781427.09
72079360.771400.76
74332160.761398.39
76656640.761386.02
79052800.771407.95
81530880.761398.48
MAXIMAL WRITE BANDWIDTH
10247.7714210.38
MEMORY COPY BANDWIDTH TEST
==========================
Size(bytes)Bandwidth(bytes/cycle)Bandwidth(MB/s)
10245.8210648.75
20486.2511431.17
30726.1811309.64
40966.3311583.39
51206.2511429.84
61446.3511607.8
71686.2911510.59
81926.3411599.43
92166.3111531.02
102406.3611622.61
112646.3211551.17
122886.3411599.04
133126.3211555.78
143366.3511620.62
153606.1711287.61
163846.1211196.41
174083.957228.88
184322.915326.2
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215042.965417.67
225282.935357.97
235522.965414.54
2457635491.85
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276482.975435.02
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460802.995463.01
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5017635481.14
5222435484.35
542722.995470.94
5632035484.3
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624642.995474.95
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7270435491.62
757762.995472.22
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8192035485.19
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880642.995465.31
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972803.015499.31
10035235490.08
10444835491.96
1085443.015496.4
11264035490.72
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1208323.015502.93
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1873923.015507.25
1935363.015502.67
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2068483.025513.68
21401635481.46
2211843.015503.89
2283523.025517.06
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2519043.015496.48
2600963.015502.12
2682883.015497.64
27750435489.9
2867202.975435.19
2959362.995467.49
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4085762.995465.03
4218882.975434.2
4352002.985452.61
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5806082.975436.67
5990402.95305.18
6184962.965412.74
6379522.975426.45
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6799362.965415.67
7014402.975426.47
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7475202.965412.62
7710722.925334.95
7956482.895288.48
8212482.815132.24
8478722.845188.02
8744962.734989.11
9021442.745004.81
9308162.624794.01
9605122.474511.26
9912322.314223.45
10229762.163958.48
10557441.993644.64
10895361.522771.07
11243521.332424.51
11601921.182149.8
11970561.12009.58
12349441.031874.84
12738561.041896.16
13137921.011847.3
13557760.991815.14
13987840.951733.94
14428160.921690.97
14888960.911662.4
15360000.891631.91
15841280.871592.98
16343040.861576.36
16855040.851555.82
17387520.841535.8
17940480.821501.29
18503680.811484.7
19087360.81459.02
19691520.791442.87
20316160.791444.34
20951040.781422.38
21606400.771404.3
22282240.761390.2
22978560.751379.78
23705600.741360.23
24453120.741358.37
25221120.731336.56
26009600.731332.53
26828800.721309.32
27668480.711306.57
28538880.71287.96
29440000.711294.49
30361600.71274.23
31313920.691265.65
32296960.691258.17
33310720.681247.35
34355200.681248.1
35430400.671232.97
36546560.671221.7
37693440.671216.35
38881280.661212.83
40099840.661206.05
41359360.651189.26
42659840.651183.24
44001280.641165.64
45383680.651184.89
46807040.641164.57
48271360.651190.02
49786880.631155.19
51343360.641163.24
52951040.641162.7
54609920.641168.97
56320000.651183.23
58081280.631160.75
59904000.631151.1
61777920.631158.05
63713280.641171.36
65710080.641170.73
67768320.631151.42
69888000.641168.89
72079360.631157.37
74332160.641167.04
76656640.641171.26
79052800.631153.88
81530880.641176.82
MAXIMAL COPY BANDWIDTH
102406.3611622.61
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Cache Use JargonCache Hit: the data that the CPU needs right now are already in cache.Cache Miss: the data that the CPU needs right now are not currently in cache.If all of your data are small enough to fit in cache, then when you run your program, youll get almost all cache hits (except at the very beginning), which means that your performance could be excellent!Sadly, this rarely happens in real life: most problems of scientific or engineering interest are bigger than just a few MB.Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*Supercomputing in Plain English: Storage HierarchyTue Feb 15 2011
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
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Cache LinesA cache line is a small, contiguous region in cache, corresponding to a contiguous region in RAM of the same size, that is loaded all at once.Typical size: 32 to 1024 bytesExamplesCore 2 Duo [26]L1 data cache: 64 bytes per lineL2 cache: 64 bytes per linePOWER7 [28]L1 instruction cache: 128 bytes per lineL1 data cache: 128 bytes per lineL2 cache: 128 bytes per lineL3 cache: 128bytes per line Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*Supercomputing in Plain English: Storage HierarchyTue Feb 15 2011
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
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How Cache WorksWhen you request data from a particular address in Main Memory, heres what happens:The hardware checks whether the data for that address is already in cache. If so, it uses it.Otherwise, it loads from Main Memory the entire cache line that contains the address.For example, on a 1.83 GHz Pentium4 Core Duo (Yonah), a cache miss makes the program stall (wait) at least 48 cycles (26.2 nanoseconds) for the next cache line to load time that could have been spent performing up to 192 calculations! [26]Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*Supercomputing in Plain English: Storage HierarchyTue Feb 15 2011
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
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If Its in Cache, Its Also in RAMIf a particular memory address is currently in cache, then its also in Main Memory (RAM).That is, all of a programs data are in Main Memory, but some are also in cache.Well revisit this point shortly.Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*Supercomputing in Plain English: Storage HierarchyTue Feb 15 2011
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
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Mapping Cache Lines to RAMMain memory typically maps into cache in one of three ways:Direct mapped (occasionally)Fully associative (very rare these days)Set associative (common)DONTPANIC!Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*Supercomputing in Plain English: Storage HierarchyTue Feb 15 2011
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
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Direct Mapped CacheDirect Mapped Cache is a scheme in which each location in main memory corresponds to exactly one location in cache (but not the reverse, since cache is much smaller than main memory).Typically, if a cache address is represented by c bits, and a main memory address is represented by m bits, then the cache location associated with main memory address A is MOD(A,2c); that is, the lowest c bits of A.Example: POWER4 L1 instruction cacheSupercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*Supercomputing in Plain English: Storage HierarchyTue Feb 15 2011
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
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Direct Mapped Cache IllustrationSupercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*Must go intocache address11100101Main Memory Address0100101011100101Notice that 11100101 is the low 8 bits of 0100101011100101.
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
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Jargon: Cache ConflictSuppose that the cache address 11100101 currently contains RAM address 0100101011100101.But, we now need to load RAM address 1100101011100101, which maps to the same cache address as 0100101011100101.This is called a cache conflict : the CPU needs a RAM location that maps to a cache line already in use.In the case of direct mapped cache, every cache conflict leads to the new cache line clobbering the old cache line.This can lead to serious performance problems.Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*Supercomputing in Plain English: Storage HierarchyTue Feb 15 2011
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
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Problem with Direct Mapped: F90If you have two arrays that start in the same place relative to cache, then they might clobber each other all the time: no cache hits!Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*REAL,DIMENSION(multiple_of_cache_size) :: a, b, cINTEGER :: index
DO index = 1, multiple_of_cache_size a(index) = b(index) + c(index)END DOIn this example, a(index), b(index) and c(index) all map to the same cache line, so loading c(index) clobbers b(index) no cache reuse!Supercomputing in Plain English: Storage HierarchyTue Feb 15 2011
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
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Problem with Direct Mapped: CIf you have two arrays that start in the same place relative to cache, then they might clobber each other all the time: no cache hits!Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*float a[multiple_of_cache_size], b[multiple_of_cache_size, c[multiple_of_cache_size];int index;
for (index = 0; index < multiple_of_cache_size; index++) { a[index] = b[index] + c[index]; }In this example, a[index], b[index] and c[index] all map to the same cache line, so loading c[index] clobbers b[index] no cache reuse!Supercomputing in Plain English: Storage HierarchyTue Feb 15 2011
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
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Fully Associative CacheFully Associative Cache can put any line of main memory into any cache line.Typically, the cache management system will put the newly loaded data into the Least Recently Used cache line, though other strategies are possible (e.g., Random, First In First Out, Round Robin, Least Recently Modified).So, this can solve, or at least reduce, the cache conflict problem.But, fully associative cache tends to be expensive, so its pretty rare: you need Ncache. NRAM connections!Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*Supercomputing in Plain English: Storage HierarchyTue Feb 15 2011
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
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Fully Associative IllustrationSupercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*Could go intoany cache lineMain Memory Address0100101011100101
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
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Set Associative CacheSet Associative Cache is a compromise between direct mapped and fully associative. A line in main memory can map to any of a fixed number of cache lines.For example, 2-way Set Associative Cache can map each main memory line to either of 2 cache lines (e.g., to the Least Recently Used), 3-way maps to any of 3 cache lines, 4-way to 4 lines, and so on.Set Associative cache is cheaper than fully associative you need K . NRAM connections but more robust than direct mapped.Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*Supercomputing in Plain English: Storage HierarchyTue Feb 15 2011
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
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2-Way Set Associative IllustrationSupercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*Could go into cache address11100101Main Memory Address0100101011100101Could go intocache address01100101OR
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
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Cache Associativity ExamplesCore 2 Duo [26]L1 data cache: 8-way set associativeL2 cache: 8-way set associativePOWER4 [12]L1 instruction cache: direct mappedL1 data cache: 2-way set associativeL2 cache: 8-way set associativeL3 cache: 8-way set associativePOWER7 [28]L1 instruction cache: 4-way set associativeL1 data cache: 8-way set associativeL2 cache: 8-way set associativeL3 cache: 8-way set associative
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*Supercomputing in Plain English: Storage HierarchyTue Feb 15 2011
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
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If Its in Cache, Its Also in RAMAs we saw earlier:If a particular memory address is currently in cache, then its also in Main Memory (RAM).That is, all of a programs data are in Main Memory, but some are also in cache.Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*Supercomputing in Plain English: Storage HierarchyTue Feb 15 2011
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
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Changing a Value Thats in CacheSuppose that you have in cache a particular line of main memory (RAM).If you dont change the contents of any of that lines bytes while its in cache, then when it gets clobbered by another main memory line coming into cache, theres no loss of information.But, if you change the contents of any byte while its in cache, then you need to store it back out to main memory before clobbering it. Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*Supercomputing in Plain English: Storage HierarchyTue Feb 15 2011
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
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Cache Store StrategiesTypically, there are two possible cache store strategies:Write-through: every single time that a value in cache is changed, that value is also stored back into main memory (RAM).Write-back: every single time that a value in cache is changed, the cache line containing that cache location gets marked as dirty. When a cache line gets clobbered, then if it has been marked as dirty, then it is stored back into main memory (RAM). [14] Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*Supercomputing in Plain English: Storage HierarchyTue Feb 15 2011
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
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Cache Store ExamplesCore 2 Duo [26]L1 cache: write-backPentium D [26]L1 cache: write-throughSupercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*Supercomputing in Plain English: Storage HierarchyTue Feb 15 2011
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
-
The Importance of Being Local[15]
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
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More Data Than CacheLets say that you have 1000 times more data than cache. Then wont most of your data be outside the cache?
YES!
Okay, so how does cache help?Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*Supercomputing in Plain English: Storage HierarchyTue Feb 15 2011
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
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Improving Your Cache Hit RateMany scientific codes use a lot more data than can fit in cache all at once.Therefore, you need to ensure a high cache hit rate even though youve got much more data than cache.So, how can you improve your cache hit rate?Use the same solution as in Real Estate:Location, Location, Location!Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*Supercomputing in Plain English: Storage HierarchyTue Feb 15 2011
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
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Data LocalityData locality is the principle that, if you use data in a particular memory address, then very soon youll use either the same address or a nearby address.Temporal locality: if youre using address A now, then youll probably soon use address A again.Spatial locality: if youre using address A now, then youll probably soon use addresses between A-k and A+k, where k is small.Note that this principle works well for sufficiently small values of soon.Cache is designed to exploit locality, which is why a cache miss causes a whole line to be loaded.Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*Supercomputing in Plain English: Storage HierarchyTue Feb 15 2011
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
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Data Locality Is Empirical: CData locality has been observed empirically in many, many programs.Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*void ordered_fill (float* array, int array_length){ /* ordered_fill */ int index;
for (index = 0; index < array_length; index++) { array[index] = index; } /* for index */} /* ordered_fill */
Supercomputing in Plain English: Storage HierarchyTue Feb 15 2011
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
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Data Locality Is Empirical: F90Data locality has been observed empirically in many, many programs.Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*SUBROUTINE ordered_fill (array, array_length) IMPLICIT NONE INTEGER,INTENT(IN) :: array_length REAL,DIMENSION(array_length),INTENT(OUT) :: array INTEGER :: index
DO index = 1, array_length array(index) = index END DOEND SUBROUTINE ordered_fill
Supercomputing in Plain English: Storage HierarchyTue Feb 15 2011
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
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No Locality Example: CIn principle, you could write a program that exhibited absolutely no data locality at all:Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*void random_fill (float* array, int* random_permutation_index, int array_length){ /* random_fill */ int index;
for (index = 0; index < array_length; index++) { array[random_permutation_index[index]] = index; } /* for index */} /* random_fill */Supercomputing in Plain English: Storage HierarchyTue Feb 15 2011
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
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No Locality Example: F90In principle, you could write a program that exhibited absolutely no data locality at all:Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*SUBROUTINE random_fill (array, random_permutation_index, array_length) IMPLICIT NONE INTEGER,INTENT(IN) :: array_length INTEGER,DIMENSION(array_length),INTENT(IN) :: && random_permutation_index REAL,DIMENSION(array_length),INTENT(OUT) :: array INTEGER :: index
DO index = 1, array_length array(random_permutation_index(index)) = index END DOEND SUBROUTINE random_fillSupercomputing in Plain English: Storage HierarchyTue Feb 15 2011
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
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Permuted vs. OrderedSupercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*In a simple array fill, locality provides a factor of 8 to 20 speedup over a randomly ordered fill on a Pentium4.
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
Permuted vs Ordered
27.251.379997
11.070.76
4.050.36
1.640.18
0.710.09
0.350.04
0.180.02
0.080.01
Random
Ordered
Array size (log2 bytes)
CPU seconds
Sheet1
Sizelog(size)RandomOrdered
1342177282727.251.379997
671088642611.070.76
33554432254.050.36
16777216241.640.18
8388608230.710.09
4194304220.350.04
2097152210.180.02
1048576200.080.01
Sheet2
Sheet3
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Exploiting Data LocalityIf you know that your code is capable of operating with a decent amount of data locality, then you can get speedup by focusing your energy on improving the locality of the codes behavior.This will substantially increase your cache reuse.Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*Supercomputing in Plain English: Storage HierarchyTue Feb 15 2011
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
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A Sample ApplicationMatrix-Matrix MultiplyLet A, B and C be matrices of sizesnr nc, nr nk and nk nc, respectively:Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*The definition of A = B C isfor r {1, nr}, c {1, nc}.Supercomputing in Plain English: Storage HierarchyTue Feb 15 2011
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
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Matrix Multiply w/InitializationSUBROUTINE matrix_matrix_mult_by_init (dst, src1, src2, & & nr, nc, nq) IMPLICIT NONE INTEGER,INTENT(IN) :: nr, nc, nq REAL,DIMENSION(nr,nc),INTENT(OUT) :: dst REAL,DIMENSION(nr,nq),INTENT(IN) :: src1 REAL,DIMENSION(nq,nc),INTENT(IN) :: src2
INTEGER :: r, c, q
DO c = 1, nc DO r = 1, nr dst(r,c) = 0.0 DO q = 1, nq dst(r,c) = dst(r,c) + src1(r,q) * src2(q,c) END DO !! q END DO !! r END DO !! cEND SUBROUTINE matrix_matrix_mult_by_init
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*Supercomputing in Plain English: Storage HierarchyTue Feb 15 2011
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
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Matrix Multiply w/Initializationvoid matrix_matrix_mult_by_init ( float** dst, float** src1, float** src2, int nr, int nc, int nq){ /* matrix_matrix_mult_by_init */ int r, c, q;
for (r = 0; r < nr; r++) { for (c = 0; c < nc; c++) { dst[r][c] = 0.0; for (q = 0; q < nq; q++) { dst[r][c] = dst[r][c] + src1[r][q] * src2[q][c]; } /* for q */ } /* for c */ } /* for r */} /* matrix_matrix_mult_by_init */Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*Supercomputing in Plain English: Storage HierarchyTue Feb 15 2011
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
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Matrix Multiply Via IntrinsicSUBROUTINE matrix_matrix_mult_by_intrinsic ( & & dst, src1, src2, nr, nc, nq) IMPLICIT NONE INTEGER,INTENT(IN) :: nr, nc, nq REAL,DIMENSION(nr,nc),INTENT(OUT) :: dst REAL,DIMENSION(nr,nq),INTENT(IN) :: src1 REAL,DIMENSION(nq,nc),INTENT(IN) :: src2
dst = MATMUL(src1, src2)END SUBROUTINE matrix_matrix_mult_by_intrinsic
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*Supercomputing in Plain English: Storage HierarchyTue Feb 15 2011
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
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Matrix Multiply BehaviorSupercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*If the matrix is big, then each sweep of a row will clobber nearby values in cache.
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
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Performance of Matrix MultiplySupercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
Chart1
0.020.010.01
0.050.050.03
0.10.110.08
0.380.760.28
1.782.180.58
8.979.592.4
17.920.984.72
72.881.4618.76
156.6161.4437.41
723.9690.98151.55
Naive
Init
Intrinsic
Total Problem Size in bytes (nr*nc+nr*nq+nq*nc)
CPU sec
Matrix-Matrix Multiply
Sheet1
819200.020.010.01
1966080.050.050.03
3276800.10.110.08
7864320.380.760.28
13107201.782.180.58
31457288.979.592.4
524288017.920.984.72
1258291272.881.4618.76
20971520156.6161.4437.41
50331648723.9690.98151.55
Sheet2
Sheet3
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TilingSupercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
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TilingTile: a small rectangular subdomain of a problem domain. Sometimes called a block or a chunk.Tiling: breaking the domain into tiles.Tiling strategy: operate on each tile to completion, then move to the next tile.Tile size can be set at runtime, according to whats best for the machine that youre running on.Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR*Supercomputing in Plain English: Storage HierarchyTue Feb 15 2011
Supercomputing in Plain English: Storage Hierarchy INSTITUTION, DAY MONTH DATE YEAR
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Tiling Code: F90SUBROUTINE mat