veprof

VE process profiler running on VH

this is work in progress, expect output format changes.

Goal of this tool is to get a profile of an application running on VE card without instrumenting the executable in any way, with lowest possible overhead. The executable has to contain symbols.

Output is a textfile containing performance counters and routine names, which can be viewed with veprof_display.

The idea is to complement the relatively expensive (in terms of overhead) but precise ftrace tool with something less precise but cheaper.

Do not use with openmp codes for the moment, see bugs section.

usage

sample with 100hz:

./veprof ./exe

sample with 50 hz

./veprof -s 50 ./exe

sample a wrapper calling exe

./veprof -e ./exe ./wrapper.sh

sample an openmp code (needs some VEOS patches beyond 1.3.2)

./veprof --openmp ./exe

display gathered results:

./veprof_display veprof.out

gives something like

FUNCTION            SAMPLES   TIME    TIME VECTIME  VTIME   VOP MFLOPS   MOPS    AVG    L1$ PRTCNF  LLC$E
                          %      %     [s]     [s]      %     %                 VLEN  MISS%    [s]   HIT%
main                  53.33  55.00    0.08    0.08 100.00 98.63  33388  67707 254.46   0.00   0.00 100.00
subroutine            46.67  45.00    0.06    0.06  96.21 98.55  32109  65167 254.46   0.00   0.00 100.00

prerequisites

• ve card
• veos > 1.3.0 (needs support for reading counters from card as well as some bug fixes)

building

make

known bugs

• sometimes application deadlock when beeing profiled (under investigation)
• very rear deadlocks with openmp codes, the application deadlocks when being profiled.

future directions

• MPI support
• profiling not only on subroutine level, but more fine grained
• may be timeline sampling