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

Marek Olšák maraeo at gmail.com
Tue May 23 10:38:29 UTC 2017

On Tue, May 23, 2017 at 2:45 AM, Michel Dänzer <michel at daenzer.net> wrote:
> 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.

Ubuntu Unity, Steam small mode (there are no tabs), Ultra settings in
Dirt Rally.

Every single time I run the game with this series, I get 700-1000MB/s
of TTM BO moves. There doesn't seem to be any randomness.

It was better without this series. (meaning it was sometimes OK, sometimes bad)


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