Circuit Placement w/ Multi-core Processors May Mike Drob Grant Furgiuele Ben Winters Advisor: Dr. Chris Chu Client: IBM Design Presentation

Project Overview Circuit Placement problem is bottleneck of physical design Currently only single-core – no threads Will attempt to parallelize some functions of the FastPlace algorithm using the linux pthreads library. Will implement RQL idea into FastPlace

Design Considerations Paralellize certain CPU and time heavy functions  Profiled existing algorithm using gprof in Linux Analyze ease of parallelizing parts of the algorithm  Spring potential energy calculation  Global Placesment (Matrix Problem)  Local refinement optimizations

Design Considerations (cont.) Cores v. Threads  Speedup only continues with more cores if there are more threads  Specify number of cores at compilation time or at run time? RQL concept  Nullify the spreading forces on a small portion of the modules with highest force  Leaves these modules at their quadratically optimal location

Paralellization Priorities Using the ISPD2005 Benchmarks Function Name% Time move_8pt_clustering_withMap50.59 update_autil_ density_move_8pt_clustering_withMap8.87 move_8pt_withMap9.17 density_move_8pt_withMap3.79 wirelen3.32 shiftBlocks2.15 density_update_autil11.72 move_8pt_PP1.47 mapcoreRegion1.31 Function Name% Time swap_move_FM40.67 v_swap_FM24.43 local_order3_FM12.41 new_compact findSegmentList3.9 distributeCells1.76 find_optimal_region1.4 flipOneSeg0.58 ilr_legalizer0.56 wirelen0.44 Global PlacementDetailed Placement

Desired Performance Gains Unit Time Taken by Top 10 Most Time Consuming Functions vs. All Other Functions

Prototyping Program which looped 10,000,000 times.  Took ~6.5 seconds on single core  With two threads on dual core, took ~3.5 seconds  With four threads on quad core, took ~2 seconds Results not quite halved / fourthed due to overhead.  Thread creation overhead  System overhead

Testing Considerations Frequent Testing  On a per method basis  Will use Valgrind to profile performance Gprof doesn’t work with threaded programs  Testing done on a variety of systems Test for consistant performance levels in comparable systems Test for increased performance in more capable systems

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Questions?