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From: Gerd Hoffmann <kraxel@redhat.com>
Date: Thu, 21 Jan 2016 10:45:32 +0100
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Subject: Re: [Qemu-devel] RFC: running the user interface in a thread ...
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To: Fam Zheng <famz@redhat.com>
Cc: David Airlie <airlied@redhat.com>, =?ISO-8859-1?Q?Marc-Andr=E9?= Lureau <mlureau@redhat.com>, qemu-devel <qemu-devel@nongnu.org>

  Hi,

> What are taking long time? Can you give a few examples?

Didn't profile things, but UI code is handling bulky graphics data,
which of course takes time, especially in case some software scaling is
involved.

For sdl-1 I remember complains about it slowing down guests alot.  IIRC
I checked a while back and figured it does some X11 stuff synchronously
(i.e. waits on X server reply) somewhere deep in the library.

With virglrenderer a new issue came up: compiling shaders can take time.

Given both opengl and ui toolkits tend to be pretty bad at
multithreading I'm not sure how well helper threads for heavier UI tasks
are going to work (I suspect that is the background of your question).

cheers,
  Gerd