Re: Using sysprof with 64bits linux

Le 29/04/2017 à 21:32, Christian Hergert a écrit :
What I use for profiling various GNOME modules is:

   -ggdb -O0 -fno-omit-frame-pointer


Thanks for the answer. I was not using -ggdb (plain -g instead), so I tried that. However, I do not understand why you use -O0. Doesn't it defeat the purpose of the profiler? I though it should be used with the optimization level to be used in the real world.

With LyX, in profiling mode (which is selectable via configure) I end up with:

AM_CXXFLAGS = -g -O2 -std=c++14  -fno-omit-frame-pointer

I changed that to repalce -g with -ggdb and gave it a go.

I'm not sure how long it's been since you used Sysprof, but many years
ago (when 32-bit x86 was prevalent), Sysprof used a custom kernel
modules to get data. A while back it was changed to use the Linux perf
kernel module. There are some differences in implementation.

I have tried both the old style version on my antique unbuntu 12.04 and the new 3.34.1 on ubuntu 17.10. On this last one, the capture stored here
shows the kind of result that I obtain when looking at the src/lyx process. I doubt that all the action happens in some weird kernel function...


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