Re: [AMDGPU][CIK] PRIME with DRI3 + stalls rendering

From: Mario Kleiner <mario.kleiner.de-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
To: Shawn Starr <shawn.starr-bJEeYj9oJeDQT0dZR+AlfA@public.gmane.org>,
	amd-gfx-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org
Cc: "Michel Dänzer" <michel-otUistvHUpPR7s880joybQ@public.gmane.org>
Subject: Re: [AMDGPU][CIK] PRIME with DRI3 + stalls rendering
Date: Wed, 16 Nov 2016 01:42:33 +0100	[thread overview]
Message-ID: <3eff28a2-e53c-74b9-4e34-6e7e206f0fc5@gmail.com> (raw)
In-Reply-To: <7436783.BjWzAA5TzI@segfault>

On 11/15/2016 09:25 AM, Shawn Starr wrote:
> On Monday, November 14, 2016 3:40:17 PM EST Shawn Starr wrote:
>> On Monday, November 14, 2016 10:40:17 AM EST Michel Dänzer wrote:
>>> On 13/11/16 06:59 AM, Shawn Starr wrote:
>>>> I'm currently trying the new fence patches that prevent tearing in PRIME
>>>> on
>>>> Bonaire CIK, it works with no tearing with latest patches from Mario,
>>>> but
>>>> there is significant frame stalls, even though the performance is higher
>>>> than running the AMDGPU as dedicated.
>>>
>>> Please elaborate on what "frame stalls" means exactly.
>>
>> It looks like vsync issues, even though if I try vblank_mode=# it still
>> shows stalling.
>>
>> I'll have to make a video to show the results and post link here.
>>
>> Thanks,
>> Shawn
>
> So, It turns out to be KDE (Kwin) fault, if I start a GNOME session, and run
> Valley, no such stalls. Even though I told KWIN to disable Vsync completely
> and disable composite on full screen windows. Seems it doesn't work right.
>
> Consider the PRIME patches working for me.
>
> Thanks,
> Shawn
>
>

Glad it works for you with GNOME.

Wrt. Kwin, KWin doesn't unredirect fullscreen windows if the display 
iGPU is Intel, apparently because sometime in the past there were bugs 
in the intel ddx related to switching between redirected and 
unredirected mode. That might explain the problem under KDE.

You'd need to disable the compositor manually (SHIFT + ALT + F12 to 
toggle at runtime) while running a fullscreen app/game that way, or the 
application needs to set some NetWM hints on its window to ask for no 
composition, or some KWin rule needs to be set for the app. I tested the 
patches under KDE Plasma 5 (KUbuntu 16.04 LTS) with composition disabled 
this way and at least my tests worked fine then.

-mario
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