Date: Mon, 8 Apr 2019 14:57:37 +0200 From: Szabolcs Nagy <nsz@...t70.net> To: musl@...ts.openwall.com Subject: Re: Profiling musl * Pascal Felber <pascal.felber@...il.com> [2019-04-08 12:15:04 +0200]: > Does anyone have experience with profiling musl? We are running into > performance issues (after modifying some of the musl code) and would like to > understand where the overheads come from, but profiling with gprof does not > work and we have issues with valgrind. Any help will be greatly appreciated. gprof is fairly intrusive anyway, statistical profiling with perf should work (perf record/perf report) sometimes it's useful to trace/count some points in the code, in principle debuggers should be able to do it, but i don't know a good tool for such thing (gdb is difficult to automate and slow, unless you use ftrace but that does not always work). (i tried uprobe with perf probe, it does system wide probing instead of just one process and it's cumbersome to use) you can always modify musl to add your own instrumentation, since it's easy to run an application with a modified musl: ./libc.so app in some cases that does not work, then unshare -rm /bin/sh -c 'mount --bind libc.so /lib/ld-musl-$arch.so.1 && app' or similar (the instrumentation code can simply be dprintf(2,...)).
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