perfiso: performance isolation for commercial latency ... · paulo tomita alex chen jack zhang...

PerfIso: Performance Isolation for Commercial Latency-Sensitive Services

Călin Iorgulescu Reza Azimi Youngjin KwonEPFL Brown University University of Texas

Sameh Elnikety Manoj Syamala Vivek Narasayya Herodotus HerodotouMicrosoft Research Cyprus University of Technology

Paulo Tomita Alex Chen Jack Zhang Junhua WangMicrosoft Bing

Interactive services must feel instantaneous

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Interactive services must feel instantaneous

≤ 0.1 s

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A single query involves hundreds of machines!

≤ 0.1 s

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Web Index


≤ 0.1 s

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≤ 0.1 s

Embarrassingly parallel search

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≤ 0.1 s


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Slowest response must be << 0.1 s


≤ 0.1 s


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Slowest response must be << 0.1 s

Multiple layers of aggregation!Just one service out of many!

Wednesday Thursday Friday Saturday Sunday Monday Tuesday

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Machines are provisioned for peak load

Request-rate variation for a Microsoft Bing sub-cluster over 1 week in 20174 / 297/12/18


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Request-rate variation for a Microsoft Bing sub-cluster over 1 week in 2017

Average load

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Average load Peak load

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>>


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Datacenters have spare resources

How can we leverage this ?

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Solution: colocate batch jobs with online services

• Get spare resources to do useful work

• Primary tenant – guaranteed performance• e.g., Bing IndexServe

• Secondary tenant – best-effort performance• e.g., Apache Spark

Primary Idle PrimaryBatch Job

Without colocation With colocation + PerfIso

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PerfIso: performance isolation for online services

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• Maintains P99 of response-times (10s of ms) under colocation

Provides performance isolation of Primary

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• 45% of the CPU is used to do useful batch work

Increases system efficiency

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• 45% of the CPU is used to do useful batch work

Increases system efficiency

• Many different interactive services and hardware setups

Deployed on over 90,000 servers

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Many papers published on performance isolation

Quasar [ASPLOS ‘14] Heracles [ISCA ‘15] Elfen [USENIX ATC ’16]

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Many papers published on performance isolation

Quasar [ASPLOS ‘14] Heracles [ISCA ‘15] Elfen [USENIX ATC ’16]

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Existing solutions do not fit our requirements

PerfIso: Requirements

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1. “Black-box”: Fewest assumptions about tenants (wider applicability)

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2. “Standalone”: Primary acts like it runs alone (negligible interference)

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2. “Standalone”: Primary acts like it runs alone (negligible interference)

3. “Integrability”: Minimize software-stack changes (easy deployment)

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Why is Performance Isolation hard?

Interactive services – highly sensitive to interference!

Leaf-servers keep 99th percentile low

• Over 10 years of optimization work!• e.g., compression, adaptive parallelism, etc.

How often does the 99th percentile occur?

• For 10,000 queries / s → 100 times / s

What happens in a 100-node fanout?

• Every query runs at the 99th percentile!

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The Primary demands many resources quickly

• Bing IndexServe: multi-threaded web-index server

➢Up to 15 threads wake up in 5𝜇s1

1Constant query rate 4,000 Q/s, 500k queries experiment

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• Burstiness due to query-processing optimizations!• some queries will spawn many workers


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• Burstiness due to query-processing optimizations!• some queries will spawn many workers

• Workload arrives in bursts – exacerbates problem


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The Primary must behave as if it were standalone

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• Primary’s resource demands must be fulfilled instantly.

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• Any delays → performance penalties incurred

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• Any resource can become a performance bottleneck.

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• Any resource can become a performance bottleneck.

If a query is delayed, it is already too late!

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PerfIso

PerfIso: Implemented as a user-mode service

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OS

Primary

PerfIso

Secondary

• Only keeps track of Secondary’s PID

PerfIso: Managed resources

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OS

CPU

Primary

PerfIso

Secondary

Blind Isolation


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OS

DISK

Primary

PerfIso

Secondary

I/O throttling

CPU


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OS

MEMORY

Primary

PerfIso

Secondary

Restrict footprint

DISKCPU


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OS

NETWORK

Primary

PerfIso

Secondary

Throttle egress packets

MEMORYDISKCPU

PerfIso: CPU is the most important resource

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OS

CPU

Primary

PerfIso

Secondary

Blind Isolation

CPU sharing without PerfIso

• Primary and Secondary compete for cores.

• Secondary is aggressive: no idle cores exist.

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Machine with 12 cores

Primary

Secondary

CPU Blind Isolation: Keep a “buffer” of idle cores

• PerfIso only knows the Secondary.

• Restrict Secondary by changing core affinities.

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Primary

Secondary


Restrict Secondary to create a buffer of idle cores.


• PerfIso only knows the Secondary.

• Restrict Secondary by changing core affinities.Primary

Secondary


Idle

Restricted Secondary

Buffer of idle cores

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• Primary is unrestricted. Secondary is restricted.

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Primary can expand into the buffer!



Primary

Secondary

Idle


• Primary is unrestricted. Secondary is restricted.


Primary can expand into the buffer!



Primary

Secondary

Idle

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CPU Blind Isolation: React to bursts from Primary

• Continuously read idle core status.

• Adjust Secondary ”slice” to maintain buffer.

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Primary

Secondary

Idle

CPU Blind Isolation: Secondary gets spare cores

• Allow Secondary to use spare idle cores.

• Release spare cores incrementally.

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Idle

Primary

Secondary

CPU Blind Isolation: We dedicate 1 core to PerfIso

• PerfIso does continuous polling → we affinitize it to 1 core.

PerfIso




Idle

Primary

Secondary

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Evaluation

Experiment testbed

Hardware

• Intel Xeon E5 – 24 cores (48 w/ HT)

• 128GB RAM

Primary: Bing IndexServe

• 569 GB index-slice

• Open-loop client

• 500,000 queries @ 2,000 Q / s

Secondary: CPU micro-benchmark

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11.65

349.08

1

10

100

1000

P9

9 la

ten

cy (

ms)

Standalone Colocated

SLO

No isolation

Single server: PerfIso protects tail-latencySecondary: CPU-intensive micro-benchmark

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11.65

349.08

1

10

100

1000

P9

9 la

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ms)


SLO

No isolation

One order of magnitude worse !


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11.65

349.08

1

10

100

1000

P9

9 la

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ms)


SLO 11.65 12.07

1

10

100

1000


No isolation PerfIso

One order of magnitude worse !


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Single server: CPU utilization 3x higher! Secondary: CPU-intensive micro-benchmark

0

20

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100

CP

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Primary Secondary

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No colocation PerfIso

21%

11.65 12.07

1

10

100

1000


67%

Single server: CPU utilization 3x higher! Secondary: CPU-intensive micro-benchmark

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20

40

60

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CP

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Primary Secondary

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No colocation PerfIso

21%

11.65 12.07

1

10

100

1000


67%46% of CPU time → useful work

Restricting CPU cycles does not workSecondary: CPU-intensive micro-benchmark

11.65

349.08

12.07

33.74

1

10

100

1000

P9

9 la

ten

cy (

ms)

Standalone No isolation

PerfIso Restrict cycles

SLO

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Secondary → 5% of CPU cycles

P99 latency – 3x higher than SLO!

Restricting CPU cores does not workSecondary: CPU-intensive micro-benchmark

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20

40

60

80

100

CP

U u

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Primary Secondary

PerfIsoStandalone Restrict cores

SLO 11.65

349.08

12.07 11.63

1

10

100

1000

P9

9 la

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ms)


PerfIso Restrict cores

21%

67%

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38%

Restricting CPU cores does not workSecondary: CPU-intensive micro-benchmark

0

20

40

60

80

100

CP

U u

tiliz

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Primary Secondary

PerfIsoStandalone Restrict cores

SLO 11.65

349.08

12.07 11.63

1

10

100

1000

P9

9 la

ten

cy (

ms)


PerfIso Restrict cores

21%

67%Provisioned for peak load→

CPU utilization ~30% lower!

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38%

020406080

100

CP

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Avg CPU Utilization %

0

1000

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4000

5000

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Time (minutes)

Top-Level Aggregator P99 latency (ms) Queries / s

1-hour run of 650 machine clusterSecondary: Machine-Learning computation

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020406080

100

CP

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Avg CPU Utilization %

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2000

3000

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5000

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Top-Level Aggregator P99 latency (ms) Queries / s

1-hour run of 650 machine cluster

Average CPU utilization is 50% - 80%!

Secondary: Machine-Learning computation

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Interesting details in the paper

• Effectiveness of static CPU isolation methods

• Restricting CPU cycles

• Restricting CPU cores

• Comparison of state-of-the-art techniques

• Managing disk, memory, and network

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PerfIso: colocate batch jobs with online services

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• Black-box: do not tailor to one specific service

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• Robustness: favor user-mode over kernel implementation

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• Headroom: some core-slack makes Primary behave like standalone

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• Headroom: some core-slack makes Primary behave like standalone

• CPU Blind Isolation → colocation without impacting service performance

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perfiso: performance isolation for commercial latency ... · paulo tomita alex chen jack zhang...

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