Re: [Xen-devel] vram_dirty vs. shadow paging dirty tracking

["Zhai, Edwin" <edwin.zhai@xxxxxxxxx>]

On Wed, Mar 14, 2007 at 11:00:17AM -0500, Anthony Liguori wrote:
> Zhai, Edwin wrote:
> >On Tue, Mar 13, 2007 at 02:32:56PM -0500, Anthony Liguori wrote:
> >  
> >>When thinking about multithreading the device model, it occurred to me 
> >>that it's a little odd that we're doing a memcmp to determine which 
> >>portions of the VRAM has changed.  Couldn't we just use dirty page 
> >>    
> >
> >we made this code to improve the user vnc responsiveness long before.
> >now QEMU has new vnc implementation to resolve this issue and this code 
> >introduce perf drop for guest of linux with X or windows.
> >  
> 
> Compared to what, just updating the full screen 30 times a second?  I 
> suspect that's not as bad as it sounds since SDL will be using a XShmImage.

removing the memcpy and having whole screen update each time has better 
performance.

> 
> The VNC minimization is done based on a timer however so sticking the 
> timer stuff into a thread is still useful.  Of course, we should be able 
> to quickly determine how useful this is by just changing SDL to update 
> the whole image...
> 
> Regards,
> 
> Anthony Liguori
> 
> >so i'd like to send a patch to revert it and make a proper solution in 
> >future.
> >
> >thanks,
> >
> >  

-- 
best rgds,
edwin

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