Bug 111043

Summary:	PBO unpacking is not accelerated
Product:	Mesa	Reporter:	Whatcookie <malcolmjestadt>
Component:	Mesa core	Assignee:	mesa-dev
Status:	RESOLVED MOVED	QA Contact:	mesa-dev
Severity:	normal
Priority:	medium	CC:	john.ettedgui
Version:	git
Hardware:	x86-64 (AMD64)
OS:	Linux (All)
Whiteboard:
i915 platform:		i915 features:

Description Whatcookie 2019-07-02 22:03:46 UTC

While investigating performance bottlenecks with RPCS3 while using Radeonsi, I came across a scene which was only getting 1FPS, while spending 99% of the CPU time in the driver. Further investigation led to the discovery that using the GL_STREAM_COPY flag instead of GL_STATIC_COPY led to performance increasing to 11fps. 

This prompted us to look into Mesa's code for an explanation, since the operation here should be moving data between GPU memory to GPU memory, and shouldn't be faster with GL_STREAM_COPY. 

We came across this https://gitlab.freedesktop.org/mesa/mesa/commit/a338dc01866ce50bf7555ee8dc08491c7f63b585 which provided an explanation for why GL_STREAM_COPY was faster. 

Anyways, point is we need PBO unpacking acceleration for this to be any faster. Even when using the GL_STREAM_COPY flag about 90% of the time spent in the graphics thread is spent in a single function in the driver. 

Thanks.

Comment 1 GitLab Migration User 2019-09-18 20:29:14 UTC

-- GitLab Migration Automatic Message --

This bug has been migrated to freedesktop.org's GitLab instance and has been closed from further activity.

You can subscribe and participate further through the new bug through this link to our GitLab instance: https://gitlab.freedesktop.org/mesa/mesa/issues/1043.

Use of freedesktop.org services, including Bugzilla, is subject to our Code of Conduct. How we collect and use information is described in our Privacy Policy.