[Nouveau] "enable ctxprog xfer only when we need it to save power" introduces big performance regression

Marcin Slusarz marcin.slusarz at gmail.com
Sat Oct 29 12:09:38 PDT 2011


On Sat, Oct 29, 2011 at 07:29:23PM +0200, Marcin Slusarz wrote:
> On Sat, Oct 29, 2011 at 07:08:01PM +0200, Marcin Slusarz wrote:
> > Hi
> > 
> > I've bisected pretty big performance regression (nv92):
> > 
> > $ git bisect good
> > b2737681d5442f05ab6419e05468c3d2511a5ced is the first bad commit
> > commit b2737681d5442f05ab6419e05468c3d2511a5ced
> > Author: Martin Peres <martin.peres at ensi-bourges.fr>
> > Date:   Sat Jul 30 23:08:45 2011 +0200
> > 
> >     drm/nv50/gr: enable ctxprog xfer only when we need it to save power
> 
> Weird, reverting it on top of current git does not restore it - in
> glxgears it's even worse (-~50%).

It seems "drm/nv50/gr: refactor initialisation" relies on the above.

So, reverting these commits:

drm/nv50/gr: typo fix, how about we not reset fifo during graph init?
drm/nv50/gr: refactor initialisation
drm/nv50/gr: enable ctxprog xfer only when we need it to save power

on top of current git restores performance to the previous state.

(First commit fixes bug in 2nd, so it needs to be reverted first)

Marcin


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