[cairo-bugs] [Bug 82002] [HSW bisected] cairo-trace(all cases) performance reduce 30%~90%

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=82002

--- Comment #2 from Bill Spitzak <spitzak at gmail.com> ---
This will disable the image filtering on xlib backends. This may not be 
a concern as it sounds like the major users of the filtering are using 
the image backend anyway. Also it was also not using it on xcb, and 
perhaps other backends that talk to a remote pixman.

A correct fix would be to make the xlib backend switch to the fallback 
only if image filtering is being done, but I don't have a good idea how 
to do that. Probably even better is to move the filtering into pixman, 
so the xrender backend will use it and thus fix xlib/xcb with no changes 
to cairo. I have posted some code for this but have not seen any feedback.

Another problem with the current one is that if BEST is used it will do 
the filtering even for the identity transform (the code in pixman does 
not do this for GOOD/BEST). It should check for this and use nearest in 
this case. I will try to add a patch for that.

On 08/01/2014 03:31 AM, bugzilla-daemon at freedesktop.org wrote:
> Chris Wilson <mailto:chris at chris-wilson.co.uk> changed bug 82002
> <https://bugs.freedesktop.org/show_bug.cgi?id=82002>
> What 	Removed 	Added
> Status 	NEW 	RESOLVED
> Resolution 	--- 	FIXED
>
> *Comment # 1 <https://bugs.freedesktop.org/show_bug.cgi?id=82002#c1> on
> bug 82002 <https://bugs.freedesktop.org/show_bug.cgi?id=82002> from
> Chris Wilson <mailto:chris at chris-wilson.co.uk> *
>
> commit 27c9923e9887bab5854ecccc81dda69687a0b9ae
> Author: Chris Wilson <chris at chris-wilson.co.uk  <mailto:chris at chris-wilson.co.uk>>
> Date:   Fri Aug 1 11:29:29 2014 +0100
>
>      xlib: Undo debug hack to force fallbacks
>
>      Remove the debug hack from
>
>      commit f337342c88092a251dc00476c4a9880d1cb90822
>      Author: Bill Spitzak <spitzak at gmail.com  <mailto:spitzak at gmail.com>>
>      Date:   Fri Jul 18 18:46:26 2014 -0700
>
>          V6 image: Use convolution filters for sample reconstruction when
> downscaling
>
>      as it forces the fallback image surface for xlib causing severe
>      performance degradation.
>
>      Bugzilla:https://bugs.freedesktop.org/show_bug.cgi?id=82002  <show_bug.cgi?id=82002>
>      Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk  <mailto:chris at chris-wilson.co.uk>>
>      Cc: Bill Spitzak <spitzak at gmail.com  <mailto:spitzak at gmail.com>>
>      Cc: Bryce Harrington <b.harrington at samsung.com  <mailto:b.harrington at samsung.com>>
>
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