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<b><a class="bz_bug_link
bz_status_NEW "
title="NEW - amdgpu.dc=1 shows performance issues with Xorg compositors when moving windows"
href="https://bugs.freedesktop.org/show_bug.cgi?id=106175#c5">Comment # 5</a>
on <a class="bz_bug_link
bz_status_NEW "
title="NEW - amdgpu.dc=1 shows performance issues with Xorg compositors when moving windows"
href="https://bugs.freedesktop.org/show_bug.cgi?id=106175">bug 106175</a>
from <span class="vcard"><a class="email" href="mailto:mceier+freedesktop@gmail.com" title="Mariusz Ceier <mceier+freedesktop@gmail.com>"> <span class="fn">Mariusz Ceier</span></a>
</span></b>
<pre>
amdgpu.dc=1 also causes performance issue with 2 games I own: "Rise of the
Tomb Raider" and "Helium Rain" (UE4 game with sources publicly available on
github).
I have 2 monitors (1st is 60Hz, 2nd in 144Hz). During tests I was using
1920x1080 resolution in both games which is 60Hz on both monitors.
1. With amdgpu.dc=0 everything is fine.
2. With amdgpu.dc=1:
The issue was showing up only in menus when cursor was visible and was in the
game window e.g. when Helium Rain was running on 2nd monitor (fullscreen)
and I was moving mouse over its window - mouse was lagging/stuttering/not
responding and Xorg server was producing messages like below in Xorg.0.log:
(II) event5 - USB Gaming Mouse: SYN_DROPPED event - some input events have
been lost.
(EE) client bug: timer event5 debounce short: offset negative (-7ms)
When I moved mouse to the 1st monitor the messages were not produced and mouse
was not lagging.
I tried few things (including switching from full dyntick system to idle
dyntick) until finally MrCooper at #xorg-devel suggested trying amdgpu.dc=0
which fixed the issue.
With amdgpu.dc=1 latencytop was showing that drm_modeset_backoff was taking
~20ms.
I was using kernel 4.17.0-rc1 and 4.17.0-rc2, Mesa 18.2.0-devel
(git-d136a5fad9) and X.Org X Server 1.19.99.904 (1.20.0 RC 4) with
xf86-video-amdgpu and radeonsi.
I'm using 1000Hz gaming mouse.</pre>
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