Stuttering / Frame drops with RS880/785G and AMD Bulldozer CPU

[Shahar Or]

2012/2/14 Michel Dänzer <michel at daenzer.net>
>
> On Mon, 2012-02-13 at 13:05 +0200, Shahar Or wrote:
> >
> > A Live image of Ubuntu Desktop 12.04 amd64 was also tested. It had the
> > same stuttering / framedrop.
>
> Have you tried a live image of a different distro?

I've tried openSUSE-12.1-GNOME-LiveCD-x86_64.iso. Same thing. Maybe a
bit worse. Using the 'performance' governor results in no stuttering,
just like in Ubuntu 11.10 (more on that below).

> > 2012/2/9 Michel Dänzer <michel at daenzer.net>
> > > On Don, 2012-02-09 at 02:03 +0200, Shahar Or wrote:
> > So I ran sysprof, which is an easy GUI and to my content I only needed
> > to press a "Start" button :). That's when the magic happened. From the
> > moment it starts the stuttering goes away. Sweet rendering smoothness
> > of divine electrical display benefaction ensues! And from the moment I
> > press "Profile" to stop it, it stops and stuttering returns OMG. And
> > this is perfectly persistent. What does this mean?
>
> Not sure...
>
> Which cpufreq governor is being used? Assuming it's one that dynamically
> changes CPU core frequencies, such as ondemand or conservative, does the
> problem go away if you switch to one that doesn't, e.g. performance or
> powersave?

This is fun.
performance: smoothness goodness
ondemand: the stuttering as demonstrated in the video
conservative: stuttering reduced to seemingly about 10% compared to ondemand
powersave: stuttering increase seemingly to about five times more than
with ondemand

When using ondemand, raising minimum frequencies results in less
stuttering. Raising the minimum frequency of all four cores to the
second step, 1.7GHz, helps a lot and and raising it to 2.5GHz results
no stuttering. This is under the limited strain of dragging windows
around in 1280x1024 in compiz, Ubuntu 11.10.