From: Daniel Vetter <firstname.lastname@example.org>
To: Karol Herbst <email@example.com>
Cc: "Christian König" <firstname.lastname@example.org>,
"Dan Moulding" <email@example.com>,
firstname.lastname@example.org, "Ben Skeggs" <email@example.com>,
Subject: Re: [Nouveau] Regression in 5.15 in nouveau
Date: Tue, 7 Dec 2021 19:30:15 +0100 [thread overview]
Message-ID: <Ya+oN5kw1Ner66zd@phenom.ffwll.local> (raw)
On Tue, Dec 07, 2021 at 06:32:06PM +0100, Karol Herbst wrote:
> On Tue, Dec 7, 2021 at 10:52 AM Christian König
> <firstname.lastname@example.org> wrote:
> > Am 06.12.21 um 19:37 schrieb Dan Moulding:
> > > On 04.12.21 17:40, Stefan Fritsch wrote:
> > >> Hi,
> > >>
> > >> when updating from 5.14 to 5.15 on a system with NVIDIA GP108 [GeForce
> > >> GT 1030] (NV138) and Ryzen 9 3900XT using kde/plasma on X (not wayland),
> > >> there is a regression: There is now some annoying black flickering in
> > >> some applications, for example thunderbird, firefox, or mpv. It mostly
> > >> happens when scrolling or when playing video. Only the window of the
> > >> application flickers, not the whole screen. But the flickering is not
> > >> limited to the scrolled area: for example in firefox the url and
> > >> bookmark bars flicker, too, not only the web site. I have bisected the
> > >> issue to this commit:
> > >>
> > >> commit 3e1ad79bf66165bdb2baca3989f9227939241f11 (HEAD)
> > > I have been experiencing this same issue since switching to 5.15. I
> > > can confirm that reverting the above mentioned commit fixes the issue
> > > for me. I'm on GP104 hardware (GeForce GTX 1070), also running KDE
> > > Plasma on X.
> > I'm still scratching my head what's going wrong here.
> > Either we trigger some performance problem because we now wait twice for
> > submissions or nouveau is doing something very nasty and not syncing
> > it's memory accesses correctly.
> > Attached is an only compile tested patch which might mitigate the first
> > problem.
> > But if it's the second then nouveau has a really nasty design issue here
> > and somebody with more background on that driver design needs to take a
> > look.
> Ben mentioned a few times that fences might be busted but we all have
> no idea what's actually wrong. So it might be that your change is
> indeed triggering something which was always broken or something else.
Description sounds a bit like we're doing a clear before Xorg has had a
chance to copy the pixmap to the frontbuffer perhaps? That would point to
a fencing issue in userspace, and somehow ignoring fences ensures that the
Xorg copy/blt completes before we get around to clearing stuff.
I'm assuming we're rendering with glamour, so is nouveau relying on kernel
implicit sync or doing it's own fencing in userspace?
> > Please test if that patch changes anything.
> > Thanks,
> > Christian.
> > >
> > > Cheers,
> > >
> > > -- Dan
Software Engineer, Intel Corporation
next prev parent reply other threads:[~2021-12-07 18:30 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <email@example.com>
2021-12-06 13:19 ` Regression in 5.15 in nouveau Thorsten Leemhuis
2021-12-06 13:41 ` Christian König
2021-12-06 18:37 ` [Nouveau] " Dan Moulding
2021-12-07 9:52 ` Christian König
2021-12-07 17:32 ` Karol Herbst
2021-12-07 18:30 ` Daniel Vetter [this message]
2021-12-07 19:01 ` Dan Moulding
2021-12-07 19:22 ` Stefan Fritsch
2021-12-07 20:45 ` Dan Moulding
2021-12-08 17:43 ` Stefan Fritsch
2021-12-09 10:25 ` Christian König
2021-12-21 17:24 ` Regression in 5.15 in nouveau #forregzbot Thorsten Leemhuis
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