xmodmap really slow

[Olivier Fourdan]

On Fri, Nov 30, 2018 at 1:06 PM Olivier Fourdan <ofourdan at redhat.com> wrote:
>
> On Fri, Nov 30, 2018 at 12:27 PM Alan Hourihane <alanh at fairlite.co.uk> wrote:
> > Running perf top while it's happening shows this....
> >
> >     26.77%  Xorg           [.] ResourceClientBits
> >     15.09%  Xorg           [.] GrabMatchesSecond
> >     12.62%  Xorg           [.] DetailSupersedesSecond.isra.1
> >     12.55%  Xorg           [.] DeletePassiveGrabFromList
> >      8.83%  Xorg           [.] GrabSupersedesSecond
> >      5.55%  Xorg           [.] AddPassiveGrabToList
> >      3.09%  Xorg           [.] DeletePassiveGrab
> >      2.00%  Xorg           [.] xi2mask_merge
> >      1.16%  libc-2.27.so   [.] _int_malloc
> >      0.92%  libc-2.27.so   [.] _int_free
> >      0.59%  Xorg           [.] XkbSendMap
> >
> > Xorg is totally frozen while this is happening. No rendering occurs at all.
>
> ResourceClientBits() has a loop, I wonder how many times it gets
> called for one xmodmap request, but we could probably cache the
> resulting value since `LimitClients` is not supposed to change once
> it's set and clients are started, that would save us the loop.

Please let me know if that patch makes any difference:

https://patchwork.freedesktop.org/series/53315/

If it helps, I'll prepare a MR.

Cheers,
Olivier