This is the mail archive of the gcc-patches@gcc.gnu.org mailing list for the GCC project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: [PATCH] Sanitize block partitioning under -freorder-blocks-and-partition


> Remember it isn't using dominance anymore. The latest patch was
> instead ensuring the most frequent path between hot blocks and the
> entry/exit are marked hot. That should be better than the dominance
> approach used in the earlier version.

Indeed, that looks more resonable approach.
Can you point me to the last version of patch? Last one I remember still
walked dominators...
> 
> > We can commit it and work on better solution incrementally but it will
> > probably mean replacing it later.  If you think it makes things easier
> > to work on it incrementally, I think the patch is OK.
> 
> Yes, I think this is a big step forward from what is there now for
> splitting, which does the splitting purely based on bb count in
> isolation. I don't have a much better solution in mind yet.
> 
> >>
> >> > - I'll try building and profiling gimp myself to see if I can
> >> > reproduce the issue with code executing out of the cold section.
> >>
> >> I have spent some time this week trying to get the latest gimp Martin
> >> pointed me to configured and built, but it took awhile to track down
> >> and configure/build all of the required versions of dependent
> >> packages. I'm still hitting some issues trying to get it compiled, so
> >> it may not yet be configured properly. I'll take a look again early
> >> next week.
> >
> > I do not think there is anything special about gimp.  You can probably
> > take any other bigger app, like GCC itself. With profiledbootstrap
> > and linker script to lock unlikely section you should get ICEs where
> > we jump into cold secton and should not.
> 
> Ok, please point me to the linker script and I will try gcc
> profiledbootstrap as well. I wanted to try gimp if possible as I
> haven't seen this much jumping to the cold section in some of the
> internal apps I tried.

You can also discuss with Martin the systemtap script to plot disk accesses
during the startup.  It is very handy for analyzing the code layout issues

It may be interesting to get similar script taking traces from valgrind
and ploting the most frequent calls in the final layout ;)

Honza


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]