[Mesa-dev] [PATCH 0/6] Mesa/Gallium vertex array state optimizations
keithw at vmware.com
Sun Feb 13 11:45:05 PST 2011
These patches look good, but have you covered the case where the application is changing the contents of vertex arrays without rebinding/notifying GL in any way?
eg. an app could do:
memcpy(varray, foo, ...);
memcpy(varray, bar, ...);
with these changes will drivers still notice the difference?
----- Original Message -----
From: "Marek Olšák" <maraeo at gmail.com>
To: mesa-dev at lists.freedesktop.org
Sent: Saturday, February 12, 2011 7:05:27 PM
Subject: [Mesa-dev] [PATCH 0/6] Mesa/Gallium vertex array state optimizations
this patch series optimizes vertex array state changes in Mesa/Gallium. The problem with the vbo module and st/mesa is that it re-binds vertex arrays every draw operation instead of only when they get changed by the application, and this series aims to address that issue.
Some new issues arose during the implemention though:
1) The VBO module didn't notify the underlying driver when it was changing buffer offsets and other vertex array properties. This is fixed in the 1st patch.
2) If we do not re-bind vertex arrays every draw operation, we must assure that the state is preserved after operations like glBlitFramebuffer. This is resolved in the 3rd patch using cso_cache.
3) Unfortunately, user buffers must be mutable in order to prevent re-binding vertex buffers because we have no way to know how large they are. Instead, a new context hook has been added to Gallium called 'redefine_user_buffer', which notifies a driver that a subrange of a user buffer should be reuploaded, and also redefines its size.
I've only tested softpipe and r300g and there were no regressions. r600g should also work and Christopher told me his Nouveau drivers should be ready for this series too.
Marek Olšák (6):
vbo: notify a driver that we change buffer offsets, strides, etc.
vbo: bind arrays only when necessary
gallium: always save and restore vertex buffers using cso_cache
gallium: remove pipe_vertex_buffer::max_index
st/mesa: set vertex arrays state only when necessary
gallium: notify drivers about possible changes in user buffer contents
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