Re: [patch/backport] CFS scheduler, -v22, for v2.6.23-rc8,v2.6.22.8, v2.6.21.7, v2.6.20.20

From: Ingo Molnar
Date: Sun Sep 30 2007 - 13:27:51 EST

* Matthew <jackdachef@xxxxxxxxx> wrote:

> Thanks for your answer (sorry, I didn't know your email had changed)
> well, this will take some time since I don't work every day & it's
> turned off most of the time, hope that is OK
> before I proceed with that data-collection:
> do you think it is possible that it might be related to "Fair group
> CPU scheduler" being selected ?

i think if you are relatively sure that the box does not have any real
3D hardware in it (supported by X) then glxgears will interact badly
with X and can cause such symptoms. In that case glxgears 'spams' the X
server with requests and everyone else suffers from that. The fair-group
scheduler indeed could shift CPU usage of X just enough (in X's favor!)
that might trigger such problems. Such "spam X" workloads often react in
a paradoxial way: a scheduler that gives X _more_ CPU time will appear
to be "less interactive".)

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