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

[Alex Deucher]

2012/2/21 Shahar Or <mightyiampresence at gmail.com>:
> 2012/2/15 Shahar Or <mightyiampresence at gmail.com>
>>
>> 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.
>
>
> Dear Michel, list,
> Is there anything else I can do in order to help diagnose this issue, please?
>
> Here is sysprof:
> http://paste.ubuntu.com/851535/
>
> Perhaps this is something with cpufreq that's working incorrectly? It
> seems unrelated to the GPU. I also get these stutterings at the
> virtual terminal.

You might ask on LKML or the cpufreq ML.

Alex