University of Colorado at Boulder Core Research Lab Operating System Support for Pipeline Parallelism on Multicore Architectures Manish Vachharajani University of Colorado at Boulder John Giacomoni

University of Colorado at Boulder Core Research Lab University of Colorado at Boulder Core Research Lab Problem UP performance at “end of life” Chip-Multiprocessor systems –Individual cores less powerful than UP –Asymmetric and Heterogeneous –10s-100s-1000s of cores What do we want from multicore system? Intel (2x2-core)MIT RAW (16-core)100-core400-core

University of Colorado at Boulder Core Research Lab University of Colorado at Boulder Core Research Lab Why Pipeline Parallelism? (Extracting Performance) Task Parallelism –Desktop Data Parallelism –Web serving –Split/Join, MapReduce, etc… Pipeline Parallelism –Video decoding –Network processing

University of Colorado at Boulder Core Research Lab University of Colorado at Boulder Core Research Lab Soft Network Processing (Soft-NP) GigE Network Properties: 1,488,095 frames/sec 672 ns/frame Frame dependencies How do we protect?

University of Colorado at Boulder Core Research Lab University of Colorado at Boulder Core Research Lab Frame Shared Memory (Soft-NP) Input (IP) Output(OP)

University of Colorado at Boulder Core Research Lab University of Colorado at Boulder Core Research Lab Low-Overhead Communication Syscalls ~170nspthread mutex ~200ns Gigabit Ethernet

University of Colorado at Boulder Core Research Lab University of Colorado at Boulder Core Research Lab FastForward Portable software only framework –~35-40ns/queue operation 2.0 GHz AMD Opteron –Architecturally tuned CLF queues Works with all consistency models Hides die-die communication (See Poster at PACT)

University of Colorado at Boulder Core Research Lab University of Colorado at Boulder Core Research Lab Zero-Stall Guarantee

University of Colorado at Boulder Core Research Lab University of Colorado at Boulder Core Research Lab Gang Scheduling Dedicate resources to pipeline applications Optimize for performance –Instead of system throughput or fairness –Computer Utility -> max(System Utilization) –Multicore system -> excess of resources. Want selective timesharing

University of Colorado at Boulder Core Research Lab University of Colorado at Boulder Core Research Lab Pipelineable OS Services

University of Colorado at Boulder Core Research Lab University of Colorado at Boulder Core Research Lab Pipelineable OS Services (2) Synchronous calls introduce too much overhead Asynchronous calls may limit parallelism Solution: OS Services with independent I/O paths

University of Colorado at Boulder Core Research Lab University of Colorado at Boulder Core Research Lab Heterogeneous Gang Scheduling Mixed stages from multiple process domains Can also mix in heterogeneous components Need a single scheduling label for every pipeline stage –Ensures simultaneous scheduling of every necessary resource Scheduling multi-domain entities

University of Colorado at Boulder Core Research Lab University of Colorado at Boulder Core Research Lab Multi-Domain Entities Pipeline private state Stage private state –State shared only with stage’s parent process The multi-domain application model respects the private data model implicit in single-domain applications while providing first- class naming for multi-domain pipelines.

University of Colorado at Boulder Core Research Lab University of Colorado at Boulder Core Research Lab Summary of Findings 1)Low-overhead communication 2)Zero-stall guarantee 1)Selective timesharing 3)Pipelineable OS services 4)Heterogenous Gang Scheduling 5)Pipelines as multi-domain applications

University of Colorado at Boulder Core Research Lab University of Colorado at Boulder Core Research Lab Questions?

University of Colorado at Boulder Core Research Lab University of Colorado at Boulder Core Research Lab Approach Turn over old rocks

University of Colorado at Boulder Core Research Lab University of Colorado at Boulder Core Research Lab Security US –Health Insurance Portability and Accountability Act –Gramm-Leach-Bliley –Sarbanes-Oxley EU –Data Protection Directive