[Mesa-dev] [PATCH 1/2] loader_dri3: Wait for pending swaps to complete before drawable_fini.

[Mario Kleiner]

On Sat, May 5, 2018 at 4:44 PM, Roman Gilg <subdiff at gmail.com> wrote:
> Without this patch plasmashell on Xserver/Mesa master freezes on me
> when opening the launcher menu (Kickoff). With the patch haven't
> experienced freezes yet.
>
> Haven't tested the Steam client yet. Might be a different problem though.
>
> Tested-by: Roman Gilg <subdiff at gmail.com>
>

Thanks. Can you see if you get any freezes in kwin_x11 by "violent
alt-tabbing" with patch 1? I've seen two such freezes within 8 hours
of normal use yesterday, each occuring when i alt-tabbed (normally)
and the switcher side panel moved out from the left. Desktop was
mostly blocked then, i assume it was kwin_x11 that got stuck. When
VT-switching to the console and attaching gdb to kwin_x11 the
backtrace showed it blocked in the loader_dri3_swapbuffer_barrier()
from patch 1. I don't know if that was the cause of the freeze, or if
something unrelated was going wrong and kwin just happens to block
there when one VT switches away from the X-Server while kwin does its
thing. Freezes happened both with compositing enabled and disabled.

So far, only using patch 2/2, i haven't seen any new freezes, but
looking at the debug output i get a lot of these when alt-tabbing:

INIT: wxh = 264 x 1062, drawable 54662577 eid 54662586
QXcbConnection: XCB error: 3 (BadWindow), sequence: 13890, resource
id: 54662577, major code: 20 (GetProperty), minor code: 0
QXcbConnection: XCB error: 3 (BadWindow), sequence: 13902, resource
id: 54662577, major code: 20 (GetProperty), minor code: 0
FINI: wxh = 264 x 1062, drawable 54662577 eid 54662586 recv_sbc 3,
send_sbc 4 PENDING 1
INIT: wxh = 264 x 1062, drawable 54662633 eid 54662644
QXcbConnection: XCB error: 3 (BadWindow), sequence: 14502, resource
id: 54662633, major code: 20 (GetProperty), minor code: 0
QXcbConnection: XCB error: 3 (BadWindow), sequence: 14514, resource
id: 54662633, major code: 20 (GetProperty), minor code: 0
FINI: wxh = 264 x 1062, drawable 54662633 eid 54662644 recv_sbc 2,
send_sbc 3 PENDING 1

Curiously my display is only 1050 pixels high, that window looks higher.

Anyway, would be good to know if patch 1/1 replaces a high frequency
of lockups of plasmashell by a low frequency of lockups of kwin_x11 if
you notice something like that.

Ideally one of the more experienced Mesa developers would find a
better solution than one of these patches, at least long-term.

thanks,
-mario