[Nouveau] [PATCH 0/2] reclocking stability improvements

[Maxim Levitsky]

On Thu, 2011-04-28 at 14:35 +0200, Martin Peres wrote:
> Le 28/04/2011 14:32, Maxim Levitsky a écrit :
> > On Thu, 2011-04-28 at 14:11 +0200, Martin Peres wrote:
> >> Good work Maxim!
> >> Can you please tell us what card you use? For what range of card is this
> >> true? I can give you access to the vbios repo so as you can contact some
> >> people for further testing if you want to :)
> > I use NV86 Geforce 8400M GS card.
> > Don't have much time though.
> Ok, cool. I got a 8600 GS from my father, I'll see if I can reproduce 
> this issue.
> 
> Too bad for your time, I'll see what I can do though. This could very 
> well explain some instability I've been encountering.
> 


And one more thing, I did a hour ago.
I documented power usage of nouveau vs nvidia.
Same settings, same kernel, only GPU drivers differ:
Result is very sad:

nvidia:
        perf level0 : ~15.8-16.0W
        perf level2 : ~16.7-17.1W
nouveau:
        perf level0 : ~20.4-20.8W
        perf level2 : ~23.0-23.5W


This means 2 things.
1. There is major source of PM improvement somewhere else
2, Clocks don't affect things much (thats why somewhat wrong clocks set
by nouveau don't show visible difference in performance/power usage.

(Note: I was under false impression that when you force nvidia to
maximum perf level, it lies to you and sets it only when device isn't
idle. Well, according to registers 0x4000-0x4040 nvidia doesn't lie...)

Also, interesting fact is that clock registers have many bits that
nouveau doesn't touch, but they sure have some meaning.
Well, reverse engineering is very tough job. In fact what nouveau
developers did is already well beyond what believed to be possible, so
no complains :-)

Speaking of report on general PM regression reported by phoronix.com,
its probably there but not as dramatic as they want it to appear.
I remember being able (with help of some smoke and mirrors) to lower
power consumption to 14W, so its higher a bit probably but not that
much.

-- 
Best regards,
        Maxim Levitsky

Visit my blog: http://maximlevitsky.wordpress.com
Warning: Above blog contains rants.