supercomputing in plain english part ii: the tyranny of the storage hierarchy henry neeman, director...

Supercomputing in Plain EnglishPart II: The Tyranny ofthe Storage HierarchyHenry Neeman, DirectorOU Supercomputing Center for Education & ResearchUniversity of OklahomaWednesday September 5 2007

OU Supercomputing Center for Education & Research

This is an experiment!Its the nature of these kinds of videoconferences that failures are guaranteed to happen!NO PROMISES!So, please bear with us. Hopefully everything will work out well enough.


Access Grid/VRVSIf youre connecting via the Access Grid or VRVS, the venue is:NCSA Venue WalkaboutIts available Wed Sep 5 2007 1:00-4:30pm Central Time, but the workshop starts at 3:00pm Central Time.Many thanks to John Chapman of U Arkansas for setting this up for us.


iLincWe only have about 40-45 simultaneous iLinc connections available.Therefore, each institution has at most one iLinc person designated.If youre the iLinc person for your institution, youve already gotten e-mail about it, so please follow the instructions.If you arent your institutions iLinc person, then you cant become it, because were completely out of iLinc connections.Many thanks to Katherine Kantardjieff of California State U Fullerton for setting this up for us.


QuickTime BroadcastIf you dont have iLinc, you can connect via QuickTime:rtsp://129.15.254.141/neeman_02.sdpWe strongly recommend using QuickTime player, since weve seen it work.When you run it, traverse the menusFile -> Open URLThen paste in the rstp URL the Movie URL space, and click OK.Many thanks to Kevin Blake of OU for setting this up.


Phone BridgeIf all else fails, you can call into our phone bridge:1-866-285-7778, access code 6483137#Please mute yourself and use the phone to listen.Dont worry, Ill call out slide numbers as we go.To ask questions, please use Google Talk or Gmail.Many thanks to Amy Apon of U Arkansas for setting this up for us, and to U Arkansas for absorbing the costs.


Google TalkTo ask questions, please use our Google Talk group chat session (text only).You need to have (or create) a gmail.com account to use Google Talk.Once youve logged in to your gmail.com account, go to:http://www.google.com/talk/and then contact the user named:oscer.sipeAlternatively, you can send your questions by e-mail to [email protected].


This is an experiment!REMINDER:Its the nature of these kinds of videoconferences that failures are guaranteed to happen!NO PROMISES!So, please bear with us. Hopefully everything will work out well enough.


Okla. Supercomputing Symposium2006 Keynote:Dan AtkinsHead of NSFsOffice ofCyberinfrastructure2004 Keynote:Sangtae KimNSF SharedCyberinfrastructureDivision Director2003 Keynote:Peter FreemanNSFComputer & InformationScience & EngineeringAssistant Director2005 Keynote:Walt BrooksNASA AdvancedSupercomputingDivision Directorhttp://symposium2007.oscer.ou.edu/2007 Keynote:Jay BoisseauDirectorTexas AdvancedComputing CenterUniv Texas AustinWed Oct 3 2007 @ OUOver 280 registrations already!Free MPI workshop Tue Oct 2!FREE Symposium! FREE Food!


OutlineWhat is the storage hierarchy?RegistersCacheMain Memory (RAM)The Relationship Between RAM and CacheThe Importance of Being LocalHard DiskVirtual Memory


What is the Storage Hierarchy?RegistersCache memoryMain memory (RAM)Hard diskRemovable media (e.g., CDROM)InternetFast, expensive, fewSlow, cheap, a lot[1]


Henrys LaptopPentium 4 Core Duo T2400 1.83 GHz w/2 MB L2 Cache2 GB (2048 MB) 667 MHz DDR2 SDRAM100 GB 7200 RPM SATA Hard DriveDVD+RW/CD-RW Drive (8x)1 Gbps Ethernet Adapter56 Kbps Phone ModemDell Latitude D620[3]


Storage Speed, Size, Cost* MFLOP/s: millions of floating point operations per second** 8 64-bit integer registers, 8 80-bit floating point registers, 16 128-bit floating point XMM registers


Registers[25]


What Are Registers?Registers are memory-like locations inside the Central Processing Unit that hold data that are being used right now in operations.Arithmetic/Logic UnitControl UnitRegistersFetch Next InstructionAddSubMultDivAndOrNotIntegerFloating PointFetch DataStore DataIncrement Instruction PtrExecute InstructionCPU


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.Example:addend in R0augend in R1ADDsum in R25712Register RiRegister RjRegister RkoperandoperandresultOperation circuitry


How Many Registers?Typically, a CPU has less than 4 KB (4096 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 POWER5+ (found in IBM p-Series supercomputers): 80 64-bit integer registers and 72 64-bit floating point registers (1,216 bytes) [12]Intel Pentium4 EM64T: 8 64-bit integer registers, 8 80-bit floating point registers, 16 128-bit floating point vector registers (400 bytes) [4]Intel Itanium2: 128 64-bit integer registers, 128 82-bit floating point registers (2304 bytes) [23]


Cache[4]


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.


From Cache to the CPUTypically, data move between cache and the CPU at speeds relatively near to that of the CPU performing calculations.351 GB/sec[7]


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 POWER4 [12]Level 1 cache: 64 KB instruction, 32 KB dataLevel 2 cache: 1440 KB unified for each 2 CPUsLevel 3 cache: 32 MB unified for each 2 CPUS


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, becausefaster => more expensive => smaller.Example: IBM POWER4 latency to the CPU [12]L1 cache: 4 cycles = 3.6 ns for 1.1 GHz CPUL2 cache: 14 cycles = 12.7 ns for 1.1 GHz CPUExample: Intel Itanium2 latency to the CPU [19]L1 cache: 1 cycle = 1.0 ns for 1.0 GHz CPUL2 cache: 5 cycles = 5.0 ns for 1.0 GHz CPUL3 cache: 12-15 cycles = 12 15 ns for 1.0 GHz CPUExample: 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


Cache & RAM LatenciesBetter[26]


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


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

==================================


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

================================


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

=======================================


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]


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


What Main Memory Looks Like012345678910536,870,911You can think of main memory as a big long 1D array of bytes.


The Relationship BetweenMain Memory & Cache


RAM is SlowCPU351 GB/sec[7]3.5 GB/sec[26] (1%)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.


Why Have Cache?CPUCache is nearly the same speedas the CPU, so the CPU doesnthave to wait nearly as long forstuff thats already in cache:it can do moreoperations per second!351 GB/sec[7]3.5 GB/sec[26] (1%)29.3 GB/sec[26] (8%)


Cache & RAM Bandwidths[26]


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

501767847.188246.82

522247853.258255.26

542727848.058246.77

563207838.118250.94

583687853.978243.19

604167853.788261.14

624647849.578248.73

645127854.248260.4

665607853.68231.9

696327847.248253.33

727047857.718177.5

757767861.58247.45

788487857.648257.7

819207860.948253.15

849927837.248255.14

880647853.538243.88

911367850.788254.16

942087860.198240.45

972807862.658235.63

1003527860.98257.26

1044487865.088261.5

1085447865.778247.68

1126407858.748247.77

1167367857.178205.32

1208327863.588238.6

1249287861.458249.15

1290247863.958235.33

1331207865.718255.3

1382407855.078243.98

1433607868.618258.39

1484807853.498236.09

1536007860.658210.25

1587207859.688254

1638407867.578253.59

1689607867.228259.73

1751047851.688246.81

1812487866.578256.6

1873927861.838241.05

1935367836.388247.16

1996807867.898243.68

2068487867.728261.13

2140167865.678240.21

2211847867.298224.45

2283527860.898257.53

2355207866.978248.44

2437127857.758256.1

2519047864.658246.46

2600967866.928256.44

2682887864.358240.2

2775047868.738256.85

2867207857.198257.51

2959367850.648260.73

3061767865.468251.95

3164167858.488259.42

3266567860.478259.32

3368967864.988261.1

3481607872.738245.37

3594247867.558259.95

3706887861.678224.83

3829767857.068237.93

3952647860.468199.36

4085767849.258257.12

4218887870.998189.58

4352007865.28215.24

4495367862.68237.23

4638727852.58248.6

4792327852.088245.84

4945927866.578258.02

5109767856.98250.85

5273607853.578230.01

5447687840.18190.94

5621767820.758177.06

5806087806.388128.59

5990407777.878140.93

6184967779.198088.6

6379527778.958101.97

6584327774.668060.33

6799367752.698101

7014407770.038094.78

7239687776.568053.9

7475207758.878101.12

7710727772.358068.58

7956487772.168095.8

8212487763.728074.29

8478727773.928083.87

8744967777.268070.48

9021447771.848099.73

9308167719.598075.81

9605127768.828096.28

9912327775.098056.91

10229767771.168086.48

10557447755.968096.3

10895367760.128078.07

11243527759.88068.23

11601927631.788054.83

11970567618.28047.63

12349447732.027956.87

12738567655.858042.72

13137927725.87996.28

13557767714.618056.72

13987847515.067858

14428167624.127895.5

14888967637.937741.66

15360007636.537945.8

15841287341.237853.66

16343047515.287781.19

16855047237.047747.09

17387527461.547250.46

17940487256.97378.14

18503686696.777106.15

19087366737.496343.97

19691526547.116249.16

20316165991.115018.53

20951045836.484482.27

21606404959.793418.65

22282244657.392772.85

22978564336.382547.29

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



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

===========================


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

==========================


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

194562.955396.99

2048035491.1

215042.965417.67

225282.935357.97

235522.965414.54

2457635491.85

256002.975432.51

266242.945384.95

276482.975435.02

286723.015498.14

296962.975440.47

307202.955403.39

317442.985447.28

3276835494.46

337922.985453.21

358402.985457.75

378882.985457.63

399362.985452.18

419842.995472.63

440322.995468.92

460802.995463.01

481282.985455.08

5017635481.14

5222435484.35

542722.995470.94

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624642.995474.95

6451235489.08

6656035481.57

696323.015505.31

7270435491.62

757762.995472.22

7884835485.58

8192035485.19

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880642.995465.31

911362.995476.62

942083.015502.87

972803.015499.31

10035235490.08

10444835491.96

1085443.015496.4

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1167363.015496.95

1208323.015502.93

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13312035486.26

1382403.015509.75

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1536003.015498.09

1587203.015495.8

1638403.015507.81

16896035495.35

1751043.015511.85

1812483.015503.42

1873923.015507.25

1935363.015502.67

1996803.015510.99

2068483.025513.68

21401635481.46

2211843.015503.89

2283523.025517.06

2355203.015500.83

2437123.025516.56

2519043.015496.48

2600963.015502.12

2682883.015497.64

27750435489.9

2867202.975435.19

2959362.995467.49

3061762.995471.84

3164162.985450.19

3266562.985458.68

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3481602.945380.86

3594242.995462.88

3706882.995467.74

3829762.985441.7

3952642.985454.69

4085762.995465.03

4218882.975434.2

4352002.985452.61

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4638722.965418.31

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4945922.985449.67

5109762.995461.12

5273602.985446.15

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5621762.985445.81

5806082.975436.67

5990402.95305.18

6184962.965412.74

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8212482.815132.24

8478722.845188.02

8744962.734989.11

9021442.745004.81

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14428160.921690.97

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15360000.891631.91

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16343040.861576.36

16855040.851555.82

17387520.841535.8

17940480.821501.29

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19087360.81459.02

19691520.791442.87

20316160.791444.34

20951040.781422.38

21606400.771404.3

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23705600.741360.23

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26828800.721309.32

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69888000.641168.89

72079360.631157.37

74332160.641167.04

76656640.641171.26

79052800.631153.88

81530880.641176.82

MAXIMAL COPY BANDWIDTH

102406.3611622.61

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.


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 bytesExamplesPentium 4 (Yonah) [26]L1 data cache: 64 bytes per lineL2 cache: 128 bytes per linePOWER4 [12]L1 instruction cache: 128 bytes per lineL1 data cache: 128 bytes per lineL2 cache: 128 bytes per lineL3 cache: 512 bytes per line


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]


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.


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!


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 cache


Direct Mapped Cache IllustrationMust go intocache address11100101Main Memory Address0100101011100101Notice that 11100101 is the low 8 bits of 0100101011100101.


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.


Problem with Direct MappedIf 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!REAL,DIMENSION(multiple_of_cache_size) :: a, b, cINTEGER :: index

DO index = 1, multiple_of_cache_size a(index) = b(index) + c(index)END DO !! index = 1, multiple_of_cache_sizeIn 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!


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!


Fully Associative IllustrationCould go intoany cache lineMain Memory Address0100101011100101


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.


2-Way Set Associative IllustrationCould go into cache address11100101Main Memory Address0100101011100101Could go intocache address01100101OR


Cache Associativity ExamplesPentium 4 EM64T (Yonah) [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 associative


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.


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.


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]


The Importance of Being Local[15]


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?


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!


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.


Data Locality Is EmpiricalData locality has been observed empirically in many, many programs.void ordered_fill (int* array, int array_length){ /* ordered_fill */ int index;

for (index = 0; index < array_length; index++) { array[index] = index; } /* for index */} /* ordered_fill */


No Locality ExampleIn principle, you could write a program that exhibited absolutely no data locality at all:void random_fill (int* 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 */


Permuted vs. OrderedIn a simple array fill, locality provides a factor of 8 to 20 speedup over a randomly ordered fill on a Pentium4.


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

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.


A Sample ApplicationMatrix-Matrix MultiplyLet A, B and C be matrices of sizesnr nc, nr nk and nk nc, respectively:The definition of A = B C isfor r {1, nr}, c {1, nc}.


Matrix Multiply: Nave VersionSUBROUTINE matrix_matrix_mult_by_naive (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

CALL matrix_set_to_scalar(dst, nr, nc, 1, nr, 1, nc, 0.0) DO c = 1, nc DO r = 1, nr DO q = 1, nq dst(r,c) = dst(r,c) + src1(r,q) * src2(q,c) END DO !! q = 1, nq END DO !! r = 1, nr END DO !! c = 1, ncEND SUBROUTINE matrix_matrix_mult_by_naive


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 = 1, nq END DO !! r = 1, nr END DO !! c = 1, ncEND SUBROUTINE matrix_matrix_mult_by_init


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


Matrix Multiply BehaviorIf the matrix is big, then each sweep of a row will clobber nearby values in cache.


Performance of Matrix Multiply


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

Tiling


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.


Tiling CodeSUBROUTINE matrix_matrix_mult_by_tiling (dst, src1, src2, nr, nc, nq, & & rtilesize, ctilesize, qtilesize) 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,INTENT(IN) :: rtilesize, ctilesize, qtilesize

INTEGER :: rstart, rend, cstart, cend, qstart, qend

DO cstart = 1, nc, ctilesize cend = cstart + ctilesize - 1 IF (cend > nc) cend = nc DO rstart = 1, nr, rtilesize rend = rstart + rtilesize - 1 IF (rend > nr) rend = nr DO qstart = 1, nq, qtilesize qend = qstart + qtilesize - 1 IF (qend > nq) qend = nq CALL matrix_matrix_mult_tile(dst, src1, src2, nr, nc, nq, & & rstart, rend, cstart, cend, qstart, qend) END DO !! qstart = 1, nq, qtilesize END DO !! rstart = 1, nr, rtilesize END DO !! cstart = 1, nc, ctilesizeEND SUBROUTINE matrix_matrix_mult_by_tiling


Multiplying Within a TileSUBROUTINE matrix_matrix_mult_tile (dst, src1, src2, nr, nc, nq, & & rstart, rend, cstart, cend, qstart, qend) 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,INTENT(IN) :: rstart, rend, cstart, cend, qstart, qend

INTEGER :: r, c, q

DO c = cstart, cend DO r = rstart, rend IF (qstart == 1) dst(r,c) = 0.0 DO q = qstart, qend dst(r,c) = dst(r,c) + src1(r,q) * src2(q,c) END DO !! q = qstart, qend END DO !! r = rstart, rend END DO !! c = cstart, cendEND SUBROUTINE matrix_matrix_mult_tile


Performance with Tiling


The Advantages of TilingIt allows your code to exploit data locality better, to get much more cache reuse: your code runs faster!Its a relatively modest amount of extra coding (typically a few wrapper functions and some changes to loop bounds).If you dont need tiling because of the hardware, the compiler or the problem size then you can turn it off by simply setting the tile size equal to the problem size.


Will Tiling Always Work?Tiling WONT always work. Why?Well, tiling works well when:the order in which calculations occur doesnt matter much, ANDthere are lots and lots of calculations to do for each memory movement.If either condition is absent, then tiling wont help.


Hard Disk


Why Is Hard Disk Slow?Your hard disk is much much slower than main memory (factor of 10-1000). Why?Well, accessing data on the hard disk involves physically moving:the disk platterthe read/write headIn other words, hard disk is slow because objects move much slower than electrons: Newtonian speeds are much slower than Einsteinian speeds.


I/O StrategiesRead and write the absolute minimum amount.Dont reread the same data if you can keep it in memory.Write binary instead of characters.Use optimized I/O libraries like NetCDF [17] and HDF [18].


Avoid Redundant I/OAn actual piece of code seen at OU:for (thing = 0; thing < number_of_things; thing++) { for (time = 0; time < number_of_timesteps; time++) { read(file[time]); do_stuff(thing, time); } /* for time */} /* for thing */Improved version:for (time = 0; time < number_of_timesteps; time++) { read(file[time]); for (thing = 0; thing < number_of_things; thing++) { do_stuff(thing, time); } /* for thing */} /* for time */Savings (in real life): factor of 500!


Write Binary, Not ASCIIWhen you write binary data to a file, youre writing (typically) 4 bytes per value.When you write ASCII (character) data, youre writing (typically) 8-16 bytes per value.So binary saves a factor of 2 to 4 (typically).


Problem with Binary I/OThere are many ways to represent data inside a computer, especially floating point (real) data.Often, the way that one kind of computer (e.g., a Pentium4) saves binary data is different from another kind of computer (e.g., a POWER5).So, a file written on a Pentium4 machine may not be readable on a POWER5.


Portable I/O LibrariesNetCDF and HDF are the two most commonly used I/O libraries for scientific computing.Each has its own internal way of representing numerical data. When you write a file using, say, HDF, it can be read by a HDF on any kind of computer.Plus, these libraries are optimized to make the I/O very fast.


Virtual Memory


Virtual MemoryTypically, the amount of main memory (RAM) that a CPU can address is larger than the amount of data physically present in the computer.For example, Henrys laptop can address 32 GB of main memory (roughly 32 billion bytes), but only contains 2 GB (roughly 2 billion bytes).


Virtual Memory (contd)Locality: most programs dont jump all over the memory that they use; instead, they work in a particular area of memory for a while, then move to another area.So, you can offload onto hard disk much of the memory image of a program thats running.


Virtual Memory (contd)Memory is chopped up into many pages of modest size (e.g., 1 KB 32 KB; typically 4 KB).Only pages that have been recently used actually reside in memory; the rest are stored on hard disk.Hard disk is 10 to 1,000 times slower than main memory, so you get better performance if you rarely get a page fault, which forces a read from (and maybe a write to) hard disk: exploit data locality!


Cache vs. Virtual MemoryLines (cache) vs. pages (VM)Cache faster than RAM (cache) vs. RAM faster than disk (VM)


Storage Use StrategiesRegister reuse: do a lot of work on the same data before working on new data.Cache reuse: the program is much more efficient if all of the data and instructions fit in cache; if not, try to use whats in cache a lot before using anything that isnt in cache (e.g., tiling).Data locality: try to access data that are near each other in memory before data that are far.I/O efficiency: do a bunch of I/O all at once rather than a little bit at a time; dont mix calculations and I/O.


To Learn More Supercomputinghttp://www.oscer.ou.edu/education.phphttp://symposium2007.oscer.ou.edu/


Thanks for your attention!

Questions?


References[1] http://graphics8.nytimes.com/images/2007/07/13/sports/auto600.gif[2] http://www.vw.com/newbeetle/[3] http://img.dell.com/images/global/products/resultgrid/sm/latit_d630.jpg[4] http://en.wikipedia.org/wiki/X64 [5] Richard Gerber, The Software Optimization Cookbook: High-performance Recipes for the Intel Architecture. Intel Press, 2002, pp. 161-168.[6] http://www.anandtech.com/showdoc.html?i=1460&p=2[8] http://www.toshiba.com/taecdpd/products/features/MK2018gas-Over.shtml[9] http://www.toshiba.com/taecdpd/techdocs/sdr2002/2002spec.shtml[10] ftp://download.intel.com/design/Pentium4/manuals/24896606.pdf[11] http://www.pricewatch.com/[12] S. Behling, R. Bell, P. Farrell, H. Holthoff, F. OConnell and W. Weir, The POWER4 Processor Introduction and Tuning Guide. IBM Redbooks, 2001.[13] http

supercomputing in plain english part ii: the tyranny of the storage hierarchy henry neeman, director...

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