Exploiting Inter-Flow Relationship for Coflow Placement in Data Centers. Xin Sunny Huang, T. S. Eugene Ng Rice University

Transcription

1 Exploiting Inter-Flow Relationship for Coflow Placement in Data Centers Xin Sunny Huang, T S Eugene g Rice University

2 This Work Optimizing Coflow performance has many benefits such as avoiding application straggles [,] and improving resource utilization [,] Coflow placement is an unexplored, important factor to determine Coflow performance D-Placement leverages inter-flow relationship to find good placement for Coflows [] Orchestra (SIGCOMM ) [] Varys (SIGCOMM ) [] CARBYE (OSDI 6) [] YAR-ME (memory elasticity, in ATC 7)

3 Coflow Coflow [] : A set of parallel flows Produced by distributed applications (eg Hadoop & Spark) Performance is measured by Coflow Completion Time (CCT), ie the slowest flow s completion time Coflow # (shuffle) Coflow # (aggregation) Coflow # (broadcast) [] Chowdhury, M et al Coflow: An application layer abstraction for cluster networking (Hotets )

4 Coflow Scheduling Prior works demonstrate benefits of Coflow scheduling Limitation: Assume predetermined placement for Coflows, ie predetermined sender/receiver locations - - Existing Varys (SIGCOMM ), Aalo (SIGCOMM 5), CODA (SIGCOMM 6) and Sunflow (CoEXT 6), etc

5 Coflow Scheduling Prior works demonstrate benefits of Coflow scheduling Limitation: Assume predetermined placement for Coflows, ie predetermined sender/receiver locations - - Existing ewly arriving Varys (SIGCOMM ), Aalo (SIGCOMM 5), CODA (SIGCOMM 6) and Sunflow (CoEXT 6), etc 5

6 Coflow Placement Coflow placement can be flexible (eg cluster scheduler to choose machines for tasks in a stage) Placement and scheduling decide Coflow performance - - 6

7 Coflow Placement Coflow placement can be flexible (eg cluster scheduler to choose machines for tasks in a stage) Placement and scheduling decide Coflow performance

8 Coflow placement can be flexible (eg cluster scheduler to choose machines for tasks in a stage) Placement and scheduling decide Coflow performance 8 Coflow Placement

9 Coflow placement can be flexible (eg cluster scheduler to choose machines for tasks in a stage) Placement and scheduling decide Coflow performance 9 Coflow Placement

10 Coflow Placement Coflow placement can be flexible (eg cluster scheduler to choose machines for tasks in a stage) Placement and scheduling decide Coflow performance Finding input/output ports to place sender/receiver tasks for a newly arrival Coflow

11 Coflow Placement This work: good placement under Coflow placement can be optimal flexible scheduling (eg cluster scheduler to choose machines for tasks in a stage) Placement and scheduling decide Coflow performance Finding input/output ports to place sender/receiver tasks for a newly arrival Coflow

12 Coflow Placement Constrained by Inter-Flow Relationship Within a Coflow, flows placement are dependent

13 Coflow Placement Constrained by Inter-Flow Relationship Within a Coflow, flows placement are dependent

14 Coflow Placement Constrained by Inter-Flow Relationship Within a Coflow, flows placement are dependent

15 Coflow Placement Constrained by Inter-Flow Relationship Within a Coflow, flows placement are dependent 5

16 Coflow Placement Constrained by Inter-Flow Relationship Within a Coflow, flows placement are dependent 6

17 Challenge #: Intra-Coflow Bottleneck Delay s 0 0 r s 0 r s 50 How to place? s C 0 s 0 s 0 50 r r etwork with C in out 7

18 Challenge #: Intra-Coflow Bottleneck Delay s s r s 50 s s 0 C 0 s 0 50 r r r How to place? Only consider C : C is prioritized under optimal scheduling, and thus C is not sensitive to C etwork with C in out 8

19 Challenge #: Intra-Coflow Bottleneck Delay etwork with C C in s 0 How to place? s 0 s 0 50 r r out in Optimal out Bottleneck at r out, out, out: less bandwidth Place r at less busy port out 9

20 Challenge #: Inter-Coflow Bottleneck Contentions s C 0 s 0 s 0 r How to place? in out in Optimal out In-cast bottleneck at r in, out, out: heavily delay C (priority: C >C >C ) Place r at less busy port out 0

21 Summary: Keys to Coflow Placement Intra-Coflow Inter-Coflow Avoid delaying critical endpoints (bottleneck) Avoid contentions among critical endpoints

22 D-Placement Intra-Coflow Inter-Coflow Step : Calculate endpoint demand Identify critical endpoints that require better placement

23 D-Placement Intra-Coflow Step : Calculate endpoint demand Inter-Coflow Step : Calculate load on ports Identify critical endpoints that require better placement Find ports with less contentions

24 D-Placement Intra-Coflow Step : Calculate endpoint demand Inter-Coflow Step : Calculate load on ports Identify critical endpoints that require better placement Find ports with less contentions Avoid contentions on critical endpoints Step : Place heavily loaded endpoints on less loaded ports!

25 D-Placement Intra-Coflow Inter-Coflow r C r s s s in etwork with C out 5

26 D-Placement Intra-Coflow Inter-Coflow Step : Calculate endpoint demand r C r s s s in etwork with C out 6

27 D-Placement Intra-Coflow Step : Calculate endpoint demand Inter-Coflow Step : Calculate load on ports r C r s s s in etwork with C out 0 7

28 D-Placement Intra-Coflow Step : Calculate endpoint demand Inter-Coflow Step : Calculate load on ports r C r s s s in etwork with C out 0 Step : Place heavily loaded endpoints on less loaded ports! 8

29 D-Placement Intra-Coflow Step : Calculate endpoint demand Inter-Coflow Step : Calculate load on ports r C r s s s in etwork with C out 0 Step : Place heavily loaded endpoints on less loaded ports! 9

30 D-Placement Intra-Coflow Step : Calculate endpoint demand Inter-Coflow Step : Calculate load on ports r C r s s s in etwork with C out 0 Step : Place heavily loaded endpoints on less loaded ports! 0

31 D-Placement Intra-Coflow Step : Calculate endpoint demand Inter-Coflow Step : Calculate load on ports r C r s s s in etwork with C out 90 0 Step : Place heavily loaded endpoints on less loaded ports!

32 D-Placement Intra-Coflow Step : Calculate endpoint demand Inter-Coflow Step : Calculate load on ports r C r s s s in etwork with C out Step : Place heavily loaded endpoints on less loaded ports!

33 D-Placement Intra-Coflow Step : Calculate endpoint demand Inter-Coflow Step : Calculate load on ports r C r s s s in etwork with C out Step : Place heavily loaded endpoints on less loaded ports!

34 Intra-Coflow Step : Calculate endpoint demand D-Placement Greedy heuristic Inter-Coflow Step : Calculate load on ports r C r s s s in etwork with C out Step : Place heavily loaded endpoints on less loaded ports!

35 Simulation setup Implemented a flow-level, discrete-event simulator Workload [] : realistic trace derived from Facebook cluster hr traffic trace, > 500 Coflows, > 700,000 flows Baseline: flow-by-flow placement for Coflows (eat [] ) Coflow schedulers: Aalo [] (this talk) and Varys [] (paper), both designed to minimize average CCT by prioritizing small Coflows to avoid HOL blocking [] Varys (SIGCOMM ) [] Aalo (SIGCOMM 5) [] eat (CoEXT 6) 5

36 Improvement in Average CCT D-Placement s average-cct over eat s average-cct Aalo Lower is better x05 x075 x x5 x5 Traffic Scale Factor D-Placement improves over eat by up to % under Aalo Scheduling 6

37 Improvement in Individual CCT CCT reduction (second) Individual CCT Reduction by D-Placement from eat Reduction = Aalo Higher is better sec Small Coflows are prioritized and less sensitive to placement Large Coflows are harder to place and more sensitive to placement Ratio of Coflow bottleneck L over link bandwidth B (second) For large Coflows, D-Placement is only 085 of eat under Aalo scheduling 7

38 More in paper: Results under Varys scheduling, Sensitivity to Schedulers, 8

39 Conclusions First study on Coflow placement, which has decisive impact on Coflow performance Coflow placement is more challenging due to inter-flow dependency D-Placement leverages inter-flow relationship to find good placement for Coflows Thank You! 9

40 Thank You! Xin Sunny Huang, T S Eugene g Rice University 0

41 Backup slides

42 Sensitivity to Schedulers D-Placement s improvement over eat is usually larger under Aalo scheduling Aalo, due to lack of precise information of Coflow size, may allow temporary violation of the smallest- Coflow-first priority eat optimizes placement based on a specific traffic priority used for scheduling Thus it is prone to error in scheduling dynamics during runtime D-Placement optimizes placement in a more general case independent of the scheduling

43 Improvement in Average CCT D-Placement s average-cct over eat s average-cct Aalo Varys Lower is better x05 x075 x x5 x5 Traffic Scale Factor D-Placement improves over eat by up to 6%

44 Improvement in Individual CCT CCT reduction (second) Individual CCT Reduction by D-Placement from eat Aalo Varys Ratio of Coflow bottleneck L over link bandwidth B (second) For large Coflows, D-Placement is only 085 (09 ) of eat under Aalo (Varys) scheduling

45 Thank You! Xin Sunny Huang, T S Eugene g Rice University 5