Re: Using sysprof with 64bits linux

[Jean-Marc Lasgouttes <lasgouttes lyx org>]

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

Hi,

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
  http://www-rocq.inria.fr/~lasgoutt/sysprof-lyx.png
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...

JMarc