Some small hints for profiling utilities used on Linux systems.

gmon and gperf hints

• compile with -pg in both CFLAGS/CXXFLAGS and LDFLAGS

• use env variable GMON_OUT_PREFIX to make programs output to $GMON_OUT_PREFIX.$pid instead of gmon.out

• despite warnings, usable on multithreaded programs (all threads' times are added up), even if you can't tell individual threads apart

using linux's perf

• record: perf record -g [-o outputfile] program

• view data: perf report [-i inputfile]

When a program is running with MPI, its rank is stored in the $PMI_RANK env variable.