Blaise Barney, LLNL ASC Tri-Lab Code Development Tools Workshop Thursday, July 29, 2010 Lawrence Livermore National Laboratory, P. O. Box 808, Livermore, CA This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 memP: Lightweight Heap Profiling LLNL-PRES

Lawrence Livermore National Laboratory memP: Simple, scalable, heap profiling  memP heap profiling library provides an initial tool for examining application heap use  Helps to simplify first-pass performance analysis Easy to use: simple, reliable, low learning overhead Focus on important, yet easy to access information  Key metric: Heap High Water Mark (HWM) Maximum in-use heap allocation amount Tracks allocated memory Retains  HWM  HWM call site  Supported platforms: AMD Opteron w/ IB (TLCC, Peloton, etc.) BG/L and BG/P 1

Lawrence Livermore National Laboratory How does it work?  Allocation calls are intercepted by memP wrappers  memP wrappers call internal library functions  All information is task-local  Data collection and report generation is done arbitrarily (by runtime parameters) within MPI_Finalize  Task data is collected by the library using MPI collectives 2

Lawrence Livermore National Laboratory Using memP on LLNL's Linux Clusters 1.Important: first issue the command (interactive or in batch script): use memp 2.Compile or re-link your application with the required libraries: -L/usr/local/tools/memp/lib –lmemP –ldl 3.Set selected runtime parameters using the MEMP environment variable. For example: setenv MEMP "-x -t" More on this later... 3

Lawrence Livermore National Laboratory Using memP on LLNL's Linux Clusters 4.Run your application as usual under the srun command. For example: srun -n 16 -p pdebug a.out (interactively from login node) srun -n 64 a.out (in batch script) Or, instead of compiling/re-linking, you can also use run-time insertion of memP by using the srun-memp command. For example: srun-memp -n 16 -p pdebug a.out 5.Successful execution will produce an memP report(s). For example: memP: Storing memP output in [./a.out memP]. 4

Lawrence Livermore National Laboratory Viewing memP output  Recommended way to view memP output is with the Tool Gear viewer: Need to have run with -x included in your MEMP environment variable setting use mpipview (load Tool Gear components) setup your local X11 display environment TGui memP-outputfile  Plain text summary report also available (do not view with GUI)  Examining heap use Summary report only (text) Task report - HWM (xml) Task report - memory in use(xml)  Types of information reported depends mostly on the setting of your MEMP environment variable. 5

Lawrence Livermore National Laboratory Viewing memP output  Some useful MEMP runtime options:  Usually need to use a combination of options to get desired reports. For example, you always need -t and -x to get any useful information at the task level, and to see source code locations. ParameterEffectDefault -xGenerate XML outputOff -h [#]Task Report with HWM threshold specifiedNo Filter -i [#]Produce task "memory in use" report(s)Off -j [#]Report only on a given MPI rank. Report on all ranks -p [#]Number of HWM task entries to print (text report only)All tasks -tGenerate stack trace dataOff 6

Lawrence Livermore National Laboratory Using memP on LLNL's Linux Clusters  Example MEMP settings: setenv MEMP "-x -t" Produce an XML report that includes task HWM details and source code locations setenv MEMP "-x -t -h i 1" Same as previous plus generate one "memory in use" report per task if the specified HWM threshhold is reached. setenv MEMP "-x -t -h i 8" Same as previous but produce up to 8 "memory in use" reports per task - allows reporting on multiple locations in code that reach the specified HWM setenv MEMP "-x -t -h i 8 -j 6" Same as previous, but only generate "memory in use" reports for MPI task 6 7

Lawrence Livermore National Laboratory Viewing memP output Default text summary report MEMP unset Text summary report MEMP="-p 8" 8

Lawrence Livermore National Laboratory Viewing memP output Summary Report - HWM XML only Detail for each MPI task Callsite stack tracing Source code view MEMP="-x -t" 9

Lawrence Livermore National Laboratory Viewing memP output 10

Lawrence Livermore National Laboratory Viewing memP output Task Report - memory in use: XML only Detail for each MPI task Allocations in use by Call Site ID (CSID) Can generate multiple files/reports per task. Source code view MEMP="-x -t -i #" 11

Lawrence Livermore National Laboratory Viewing memP output Example: files/reports produced by 8-task job with MEMP="-x -t -h i 2" -rw blaise blaise Jul 20 14:03 a.out memP Summary report -rw blaise blaise Jul 20 14:03 a.out.rank memP -rw blaise blaise Jul 20 14:03 a.out.rank memP -rw blaise blaise Jul 20 14:03 a.out.rank memP Task memory in use reports -rw blaise blaise Jul 20 14:03 a.out.rank memP Up to 2 call sites per task -rw blaise blaise Jul 20 14:03 a.out.rank memP where HWM was reached -rw blaise blaise Jul 20 14:03 a.out.rank memP -rw blaise blaise Jul 20 14:03 a.out.rank memP -rw blaise blaise Jul 20 14:03 a.out.rank memP -rw blaise blaise Jul 20 14:03 a.out.rank memP -rw blaise blaise Jul 20 14:03 a.out.rank memP -rw blaise blaise Jul 20 14:03 a.out.rank memP -rw blaise blaise Jul 20 14:03 a.out.rank memP -rw blaise blaise Jul 20 14:03 a.out.rank memP -rw blaise blaise Jul 20 14:03 a.out.rank memP -rw blaise blaise Jul 20 14:03 a.out.rank memP -rw blaise blaise Jul 20 14:03 a.out.rank memP 12

Lawrence Livermore National Laboratory  Availability LLNL: Library installed in /usr/local/tools/memp/lib SNL  Module load tools/memP  /projects/tools_workshop/memP  Future Work Measuring available memory BG/P Kernel_GetMemorySize How to provide more information about OOM conditions Reporting based on time of allocation vs allocation size  References Tool Gear: John Gyllenhaal (LLNL) & John May (LLNL)  Tool POC: Chris Chambreau site Tool mail list : memP site : Availability, Future Work, References 13