[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH v2 1/2] console: add hw_screen_dump_async
From: |
Gerd Hoffmann |
Subject: |
Re: [Qemu-devel] [PATCH v2 1/2] console: add hw_screen_dump_async |
Date: |
Wed, 07 Mar 2012 07:57:57 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:10.0.1) Gecko/20120216 Thunderbird/10.0.1 |
Hi,
>> qemu is hung at:
>> main thread:
>> #0 read
>
> Is qxl doing a blocking read? If so, that's a bug in qxl.
It used to do that, with the latest spice pull it is gone[1]. And this
fix is exactly what broke screendump.
Spice does lazy rendering on the server side to avoid burning cpu for
nothing, because in the common case there is nothing to render. Thats
why there is no up-to-date displaysurface we can just write out when the
screendump command comes in.
What qxl screendump used to do is this:
(1) ask spice server to render the screen
(2) blocking read, waiting for spice spice server finish <- BUG
(3) write out screendump
What qxl screendump does now is:
(1) ask spice server to render the screen
(2) write out screendump from outdated displaysurface <- BUG
(3) spice server finished, callback comes in, arm BH
(4) bottom half handler updates displaysurface
What we like to do instead is this:
(1) ask spice server to render the screen
(2) spice server finished, callback comes in, arm BH
(3) bottom half handler updates displaysurface
and writes the screendump
(4) signal screendump monitor command is finished.
See our problem now?
cheers,
Gerd
[1] With the exception of guest with old qxl drivers which is pretty
much unfixable due to way the old guest <-> qxl interface is
designed.
- Re: [Qemu-devel] [PATCH v2 1/2] console: add hw_screen_dump_async, (continued)
- Re: [Qemu-devel] [PATCH v2 1/2] console: add hw_screen_dump_async, Alon Levy, 2012/03/06
- Re: [Qemu-devel] [PATCH v2 1/2] console: add hw_screen_dump_async, Anthony Liguori, 2012/03/06
- Re: [Qemu-devel] [PATCH v2 1/2] console: add hw_screen_dump_async, Luiz Capitulino, 2012/03/06
- Re: [Qemu-devel] [PATCH v2 1/2] console: add hw_screen_dump_async, Alon Levy, 2012/03/06
- Re: [Qemu-devel] [PATCH v2 1/2] console: add hw_screen_dump_async, Anthony Liguori, 2012/03/06
- Re: [Qemu-devel] [PATCH v2 1/2] console: add hw_screen_dump_async, Alon Levy, 2012/03/06
- Re: [Qemu-devel] [PATCH v2 1/2] console: add hw_screen_dump_async, Alon Levy, 2012/03/06
- Re: [Qemu-devel] [PATCH v2 1/2] console: add hw_screen_dump_async, Anthony Liguori, 2012/03/06
- Re: [Qemu-devel] [PATCH v2 1/2] console: add hw_screen_dump_async, Alon Levy, 2012/03/06
- Re: [Qemu-devel] [PATCH v2 1/2] console: add hw_screen_dump_async, Anthony Liguori, 2012/03/06
- Re: [Qemu-devel] [PATCH v2 1/2] console: add hw_screen_dump_async,
Gerd Hoffmann <=