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Date: Tue, 04 Nov 2008 14:51:32 -0600
From: Anthony Liguori <aliguori@us.ibm.com>
MIME-Version: 1.0
Subject: Re: [Qemu-devel] vga optmization
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To: Avi Kivity <avi@redhat.com>
Cc: Glauber Costa <glommer@redhat.com>, qemu-devel@nongnu.org

Avi Kivity wrote:
> Glauber Costa wrote:
>> My reason to do this way, was to be lazy about updating the dirty 
>> bitmap.
>> But if the common case is to check for all pages in the region, then
>> it won't matter much.
>>   
>
> In the common case we only check for the displayable area.  We should 
> split the region into two, one for the displayable area and one for 
> the offscreen framebuffer (the boundary changes dynamically with the 
> resolution).  If qemu can tell us nobody is looking at the screen, we 
> can dirty tracking altogether.

Yeah, there already is an ds->idle in the DisplayState code.  This is 
set by VNC and by SDL.

Of course, dirty updating is driven by vga_hw_update() which is driven 
by a timer who's interval is determined by ds->idle so we already do 
this in practice.

Regards,

Anthony Liguori