If you can share before/after output from -log_view, it would likely help localize. Another unintrusive thing (if you're allowed to run Linux perf) is to $ perf record --call-graph dwarf -F99 ./app [... runs ...] $ perf script | stackcollapse-perf | flamegraph > flame.svg and open flame.svg in a browser (it's interactive). This uses the flamegraph tools (https://github.com/brendangregg/FlameGraph). You can direct `perf script` to a file and share that if you can't/won't install flamegraph. This doesn't require compiling any special way and yet helps understand where time is spent. Adrian Croucher <[email protected]> writes:
hi,
We have our PETSc-based code compiled on a Cray XC-50 machine, and it has just recently started running about 2.5 times slower on there. Neither the code nor PETSc has been recompiled lately.
Turning the PETSc logging on, it appears to be spending more time on I/O than it used to.
The cluster admins have suggested we rebuild with the Cray "perftools" module loaded to get profiling info. It's a slight hassle to rebuild everything, so I wondered, would this actually tell us anything that we don't already know from the PETSc logs?
- Adrian
-- Dr Adrian Croucher Senior Research Fellow Department of Engineering Science University of Auckland, New Zealand email: [email protected] tel: +64 (0)9 923 4611