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List:       kde-commits
Subject:    Re: qt-copy
From:       Andreas Hartmetz <ahartmetz () gmail ! com>
Date:       2009-02-24 22:02:48
Message-ID: 200902242302.48826.ahartmetz () gmail ! com
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On Monday 23 February 2009 22:39:14 Fredrik Höglund wrote:
> On Monday 23 February 2009, Andreas Hartmetz wrote:
> > Looks like this completely ruins painting performance with graphicssystem
> > raster for me, both on my desktop with Radeon HD 2400 and radeonhd (open
> > source) driver and on my laptop with Intel i845 and the usual Intel
> > driver. The symptoms are e.g. choppy scrolling in KHTML and a visible
> > delay when repainting the client area of a tabwidget. Painting issues
> > with transparent GIFs in KHTML are also still there - just for
> > completeness. I was hoping to see those fixed by the patch :)
>
> The patch doesn't fix any regressions, it's about not using a deprecated
> function that many drivers (including the Intel one) no longer support.
>
> Qt would still work with those drivers, but it would end up taking a
> fallback path that doesn't use shared memory.
>
> With this change, scrolling large windows is noticeably faster for me with
> the radeon driver.
>
> > Painting now seems to be slightly slower than with graphicssystem native
> > overall, worse in some cases like in the text widget I'm writing this
> > email. I guess we need somebody to tell us what's happening here :)
> > The patch description looks sane to me, but I don't really understand X
> > performance and/or driver issues.
>
> I've attached another patch that tweaks the code a bit to avoid ending
> up in a problematic code path in the X server. It also changes the code
> to not use SHM with smaller updates, since the sync call that follows it
> can actually make it slower in that case.
>
> Does this patch fix the problems you are seeing?
>
Yes! (tested only with radeonhd driver though)
Overall painting performance may be slightly worse, but scrolling seems to be 
better. Which is important for me, so I'd vote to add this patch to patch 
0274. If there are more issues with it hopefully somebody will scream. I 
certainly will if it degrades performance on my other computer(s).

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