1. Parallel Performance Wizard: a Performance Analysis Tool for UPC (and other PGAS Models) Max Billingsley III 1, Adam Leko 1, Hung-Hsun Su 1, Dan Bonachea 2, Alan D. George 1 1 Electrical and Computer Engineering Dept., University of Florida 2 Computer Science Div., UC Berkeley

2. 2 Outline of Talk Review of PGAS talk The goal of PPW Current status of PPW Using PPW Continuing Work How can we make PPW as useful as possible?

3. 3 Review of PGAS talk Motivation for performance tools supporting PGAS models  printf() doesn’t cut it for optimizing programs writing using PGAS models such as UPC  Good tools can really enhance productivity  Currently poor support for UPC from existing tools Overview of the GASP tool interface  Event-based interface between performance tool and GAS model compiler / runtime system Overview and demonstration of PPW  New performance tool designed for PGAS models

4. 4 The goal of PPW Help UPC users  achieve maximum productivity  in optimizing the performance of their applications  by providing detailed experimental performance data and helping them make sense of this data.

5. 5 Parallel Performance Wizard – current status Beta version of PPW available now: http://www.hcs.ufl.edu/ppw/ http://www.hcs.ufl.edu/ppw/  We even have a Java WebStart version you can test-drive quickly from any computer PPW currently includes many features that should make it useful for UPC developers  UPC-specific array layout visualization PPW has complete instrumentation support on one UPC implementation  Berkeley UPC 2.3.16 beta includes complete support for PPW by implementing GASP

6. 6 Using PPW The UPC developer takes the following steps:  Build the application using PPW’s compiler wrapper scripts: ppwupcc –inst-functions -o upc_app upc_app.c  Execute the instrumented application, using the ppwrun script to set up the environment: ppwrun --pofile --output=upc_app.par upcrun -N 32./upc_app  Open the resulting file using the PPW GUI Transfer file to workstation and start GUI

7. 7 Continuing work on PPW and GASP PPW  Add Additional PPW visualization features Scalability charts  More interesting analysis functionality GASP  Add support for additional PGAS models  Help other tools take advantage of GASP

8. Nano Case Study, NPB2.4 IS

9. 9 Nano Case Study Intro PPW looks pretty, how useful is it for real apps? Examine GWU NPB2.4 IS benchmark and looked for interesting things Point of study  See if tool tells us anything interesting  NOT to pick apart a particular implementation  Example yesterday illustrated my bad UPC code

10. 10 NPB 2.4 on Marvel (8 dual-core pr. SMP)

11. 11 NPB2.4 on Mu Cluster (Quadrics & Opteron)

12. 12 Close-up of SMP Comm. Pattern

13. 13 Close-up of Cluster Comm. Pattern

14. 14 The Culprit /** * Equivalent to the mpi_alltoall + mpialltoallv in the c + mpi version * of the NAS Parallel benchmark. */ for( i=0; i<THREADS; i++ ) { upc_memget( &infos[i], &send_infos_shd[MYTHREAD][i], sizeof( send_info )); } … for(i = 0; i < THREADS; i++) { … upc_memget( key_buff2 + total_displ, key_buff1_shd + i + infos[i].displ * THREADS, infos[i].count * sizeof(INT_TYPE)) ; … } * Collectives! *

15. 15 Other Interesting Things Sum reductionBroadcast

16. 16 Interesting Reduction Find How many remote references?  upc_forall(thr_cnt=1; thr_cnt<THREADS; thr_cnt <<= 1; continue) … upc_memget(local_array, ptrs[MYTHREAD + thr_cnt], size * sizeof(elem_t)) ; … What about now?  shared elem_t *shared *ptrs ;

17. 17 Comm. Leak, Visually

18. 18 How can we make PPW as useful as possible? We would like feedback on the tool  Try the PPW beta and provide feedback!  www.hcs.ufl.edu/ppw www.hcs.ufl.edu/ppw Help us improve GASP  What can we do to help language implementers add GASP support? Other ideas regarding UPC performance analysis?

19. 19 Interoperability Some key issues  Usefulness of interoperating with other similar PGAS models?  “Dusty deck” MPI code