高级计算机体系结构设计及其在数据中心和云计算的应用Sources of (Coarse) Parallelism.Differentapplications-MP3playerinbackground whileyouwork inOffice- Other background tasks: Os/kernel, virus check, etc...- Piped applicationsgunzip-cfoo.gzIgrepbarIperlsome-script.plThreads within the same applicationJava(scheduling,GC,etc...)- Explicitly coded multi-threading.pthreads,MPl,etc
高级计算机体系结构设计及其在数据中心和云计算的应用 Sources of (Coarse) Parallelism • Different applications – MP3 player in background while you work in Office – Other background tasks: OS/kernel, virus check, etc. – Piped applications • gunzip -c foo.gz | grep bar | perl some c foo.gz | grep bar | perl some-script.pl script.pl • Threads within the same application – Java (scheduling, GC, etc.) – Explicitly coded multi-threading • pthreads, MPI, etc
高级计算机体系结构设计及其在数据中心和云计算的应用SMp MachinesSMP= SymmetricMulti-Processing- Symmetric = All cPUs have“equal" access to memoryOS seems multiple CPUs-Runsoneprocess(orthread)oneachCPUCPU。CPU,CPU2CPU3
高级计算机体系结构设计及其在数据中心和云计算的应用 SMP Machines • SMP = Symmetric Multi-Processing – Symmetric = All CPUs have “equal” access to memory • OS seems multiple CPUs – Runs one process (or thread) on each CPU CPU0 CPU1 CPU2 CPU3
高级计算机体系结构设计及其在数据中心和云计算的应用MpWorkloadBenefitsruntimeTaskATask B3-wide000CPUTaskATask B4-wide000CPUBenefit3-wide3-wideTaskATask B00000CPUCPUTaskA2-wide2-wideTask B000000CPUCPUAssumesyouhavemultipletasks/programsto run
高级计算机体系结构设计及其在数据中心和云计算的应用 MP Workload Benefits 3-wide OOO CPU Task A Task B 4-wide OOO Task A Task B runtime CPU Benefit 3-wide OOO CPU Task A Task B 3-wide OOO CPU 2-wide OOO CPU Task B 2-wide Task A OOO CPU Assumes you have multiple tasks/programs to run
高级计算机体系结构设计及其在数据中心和云计算的应用... If Only One Task AvailableruntimeTaskA3-wide000CPUTaskA4-wideBenefit000CPU3-wideTaskAWIdENobenefitoverICPU00080CPUCPUTaskA2-widePerformance0000CPUSDdegradation!Idle
高级计算机体系结构设计及其在数据中心和云计算的应用 . If Only One Task Available 3-wide OOO CPU Task A 4-wide OOO Task A Benefit runtime CPU 3-wide OOO CPU 3-wide OOO CPU Task A 2-wide OOO CPU 2-wide OOO CPU Task A Idle No benefit over 1 CPU Performance degradation!
高级计算机体系结构设计及其在数据中心和云计算的应用Benefit of Mp Depends on WorkloadLimited number of parallel tasks to run on PC-Adding moreCPUs thantasksprovidezero benefitForparallel code,Amdahl'slaw curbs speedupparallelizableICPU2CPUs3CPUs4CPUs
高级计算机体系结构设计及其在数据中心和云计算的应用 Benefit of MP Depends on Workload • Limited number of parallel tasks to run on PC – Adding more CPUs than tasks provide zero benefit • For parallel code, Amdahl’s law curbs speedup parallelizable 1CPU 2CPUs 3CPUs 4CPUs