Bug 52930

Summary: glXWaitX is often ineffective
Product: Mesa Reporter: Karl Tomlinson <bugs.freedesktop>
Component: GLXAssignee: mesa-dev
Status: RESOLVED MOVED QA Contact:
Severity: normal    
Priority: medium    
Version: 8.0   
Hardware: Other   
OS: All   
i915 platform: i915 features:

Description Karl Tomlinson 2012-07-30 01:03:55 UTC
The description of glXWaitX says "X rendering calls made prior to glXWaitX are
guaranteed to be executed before GL rendering calls made after glXWaitX", but
glXWaitX is currently a no-op when direct rendering unless the current
drawable is a window and single buffered.  In situations where
dri2_copy_drawable is used it performs the required X server round trip.

At one point in history glXWaitX called XSync with direct rendering:

It seems XSync should be used when dri2_copy_drawable is not necessary.
There is some discussion in this thread:

Perhaps LastKnownRequestProcessed NextRequest can be used to determine whether
the XSync is necessary.  They could also detect that the XSync is not necessary after dri2_copy_drawable.

glxWaitGL looks like a no-op in similar situations.
I wonder whether at least a glFlush is required here.

applegl and indirect contexts appear to support glXWaitX/GL.
Comment 1 GitLab Migration User 2019-09-18 17:44:18 UTC
-- GitLab Migration Automatic Message --

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