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authorKenneth Graunke <[email protected]>2013-10-22 22:55:33 -0700
committerKenneth Graunke <[email protected]>2013-11-07 15:52:02 -0800
commit30f61c471de5a9637e5d830e2b5b9dc4145f94d2 (patch)
tree31212072fc261412edc7194ef34d2b7404f27781 /doxygen/gallium.doxy
parent1bd623316913fdefa3749809420db27291ef9f0e (diff)
Revert "i965: Add support for GL_AMD_performance_monitor on Ironlake."
This reverts most of commit 0f2da773070c06b6d20ad264d3abb19c4dfd9761. (I chose to leave the additions to brw_defines.h.) My previous Ironlake implementation was somewhat broken: counter data was global, rather than per-context. This meant that performance monitors captured data from your compositor, 2D driver, and other 3D programs. Originally, I believed that Sandybridge and later had an easy way to avoid this problem (setting per-context flags in OACONTROL), while Ironlake did not. So I'd intended to leave it as a known limitation of performance monitoring support on Ironlake. However, this turned out not to be true. Unfortunately, our hardware only has one set of aggregating performance counters shared between all 3D programs, and their values are not saved or restored by hardware contexts. Also, at least on Sandybridge and Ivybridge, the counters lose their values if the GPU goes to sleep. To work around both of these problems, we have to snapshot the performance counters at the beginning and end of each batch, similar to how we handle query objects on platforms that don't support hardware contexts. For occlusion queries, this batch bookending approach is fairly simple: only one occlusion query can be active at a time, and the result is a single integer. Performance monitors are more complex: an arbitrary number of monitors can be active at a time, each monitoring some subset of our ~30 observability counters. Individual monitors can be started and stopped at any point during the batch. Tracking where each monitor started/ended relative to batch flushes ends up being a pain. And you can run out of space in the buffer. Properly supporting this required some serious rearchitecting of the code. Rather than writing patches to try and morph a broken system into a working one (which operates quite differently), I decided it would be simplest to revert the old code and start fresh. Parts will look familiar, but other parts are new. I also decided it would be best to include Sandybridge and Ivybridge support from the start, since the newer platforms have added complexity that I wanted to make sure worked. They're also what most people care about these days. Signed-off-by: Kenneth Graunke <[email protected]>
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