[PATCH 0/3] drm/amdgpu: Tweaks for high pressure on CPU visible VRAM

Michel Dänzer michel at daenzer.net
Tue May 23 00:45:45 UTC 2017

On 22/05/17 07:09 PM, Marek Olšák wrote:
> On Mon, May 22, 2017 at 12:00 PM, Michel Dänzer <michel at daenzer.net> wrote:
>> On 20/05/17 06:26 PM, Marek Olšák wrote:
>>> On May 20, 2017 3:26 AM, "Michel Dänzer" <michel at daenzer.net
>>> <mailto:michel at daenzer.net>> wrote:
>>>     On 20/05/17 01:14 AM, Marek Olšák wrote:
>>>     > Hi Michel,
>>>     >
>>>     > I've applied your series
>>>     Thanks for testing it.
>>>     > and it doesn't help with low Dirt Rally performance on Fiji. I see TTM
>>>     > buffer moves at 800MB/s and many VRAM page faults.
>>>     Did you see this:
>>>     >> Note that there's only little if any improvement of the average
>>>     framerate
>>>     >> reported, but the minimum framerate as seen on the HUD goes from
>>>     ~10 fps
>>>     >> to ~17.
>>>     I.e. it mostly affects the minimum framerate and smoothness for me
>>>     as well.
>>> Without the series, I get 70 average fps. With the series, I get 30
>>> average fps. That might just be random bad luck. I don't know.
>> Hmm, yeah, maybe that was just one of the random slowdowns you've been
>> talking about in other threads and on IRC?
>> I can't reproduce any slowdown with these patches, even leaving visible
>> VRAM size at 256 MB.
> The random slowdowns with Dirt Rally are only caused by the pressure
> on visible VRAM. This whole thread is about those random slowdowns.

No, this thread is about the scenario described in the cover letter of
this patch series.

> If you're saying "maybe it was just one of the random slowdowns", you're
> saying "maybe it was just the visible VRAM pressure". It's only
> random with Dirt Rally, which makes it difficult to believe statements
> such as "I can't reproduce any slowdown".

I could say the same thing about you seeing random slowdowns... I've
never seen that, I had to artificially limit the size of visible VRAM to
64 MB to make it significantly affect the benchmark result.

How many times do you need to run the benchmark on average to hit a
random slowdown? Which desktop environment and other X clients are
running during the benchmark? Which tab is active in the Steam window
while the benchmark runs?

In my case, it's only xfwm4, xterm and steam on the Dirt Rally page in
the library.

Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer

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