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Bug 522166 - New compositor performs abysmally because of artificial update limit.
New compositor performs abysmally because of artificial update limit.
Status: RESOLVED FIXED
Product: metacity
Classification: Other
Component: Iain's compositor
2.22.x
Other All
: Normal major
: ---
Assigned To: Metacity compositor maintainers
Metacity compositor maintainers
Depends on:
Blocks:
 
 
Reported: 2008-03-13 04:31 UTC by Brandon Wright
Modified: 2008-03-28 08:37 UTC
See Also:
GNOME target: ---
GNOME version: 2.21/2.22


Description Brandon Wright 2008-03-13 04:31:48 UTC 
After installing the new, stable Metacity 2.22.0, I noticed that Iain's newly integrated compositor definitely wasn't performing as well as when I tried it as the separate branch. 

I investigated, and it appears that in commit revision 3453, an artificial limit is placed on the update rate by adding a timer that only runs every 20ms (50fps), and it will even wait 20ms before updating after a region is marked. This severely hampers the compositor's performance, and makes the image update rate extremely clunky.
Comment 1 Thomas Thurman 2008-03-17 00:04:28 UTC 
Iain was the one who made that change, so he'll presumably be the best person to ask about it.
Comment 2 iain 2008-03-18 23:53:15 UTC 
How does it feel if you change the #if 0 around the timeout at line 1357 to #if 1 so that it uses an idle instead? Does that make it feel snappier?
Comment 3 Brandon Wright 2008-03-19 00:07:02 UTC 
(In reply to comment #2)
> How does it feel if you change the #if 0 around the timeout at line 1357 to #if
> 1 so that it uses an idle instead? Does that make it feel snappier?
> 
Yes, actually. I did that when I first identified the issue to make sure it was the cause.
Comment 4 iain 2008-03-19 00:49:36 UTC 
Ok, cool. I've just made the change in SVN. It doesn't make an overly noticable difference on my machine really.
Comment 5 Baptiste Mille-Mathias 2008-03-28 08:37:26 UTC 
(In reply to comment #4)
> Ok, cool. I've just made the change in SVN. It doesn't make an overly noticable
> difference on my machine really.
> 

But it noticable here, while moving a window, the redraw is smoother.

Thanks Iain