On 21 May 2013 16:52, Paul Berry <stereotype...@gmail.com> wrote: > This series implements fast color clears, a Gen7+ feature which > reduces memory bandwidth by deferring the memory writes involved in a > glClear() until the same memory is later touched during rendering. > > From a broad overview point of view, fast color clears work in a > similar way to HiZ: an auxiliary "MCS" buffer keeps track of which > parts of the buffer have been cleared but haven't yet had the > necessary memory writes performed. Whenever a color buffer needs to > be accessed by the CPU, or by a part of the GPU that is not > fast-color-aware, we have to perform a "resolve operation" to force > any pending memory writes to occur. > > This patch series adopts a slightly different strategy (compared to > HiZ) for making sure the resolves happen when needed. Instead of > modifying each code path that might need to do a resolve so that it > does one if needed, we create an accessor function that does the > resolve if needed and then provides the caller with access to the > miptree's underlying memory region. This lets us have a lot more > confidence that we didn't miss any code paths, which is important > since color buffers are accessed by a large number of code paths. To > discourage future maintainers from trying to bypass the accessor > function, it is inline (so that overhead is negligible), and the field > it provides access to has been renamed to region_private. > > Patch 01 ifdefs out some code so that it does not appear in the i915 > (pre-Gen4) driver--this makes it easier to be confident that these > changes won't regress i915. Patch 02 introduces the aforementioned > accessor function. Patches 03-11 are the guts of the implementation, > and patch 12 enables the new feature. > > No piglit regressions. I have additional piglit tests which validate > specific important corner cases--I hope to get those out to the list > later this week. > > [PATCH 01/12] intel: Conditionally compile mcs-related code for i965 only. > [PATCH 02/12] intel: Create intel_miptree_get_region() to prepare for fast > color clear. > [PATCH 03/12] i965/gen7+: Create an enum for keeping track of fast color > clear state. > [PATCH 04/12] i965/gen7+: Set up MCS in SURFACE_STATE whenever MCS is > present. > [PATCH 05/12] i965/gen7+: Create helper functions for single-sample MCS > buffers. > [PATCH 06/12] i965/gen7+: Implement fast color clear operation in BLORP. > [PATCH 07/12] i965/blorp: Expand clear class hierarchy to prepare for RT > resolves. > [PATCH 08/12] i965/blorp: Write blorp code to do render target resolves. > [PATCH 09/12] i965/gen7+: Ensure that front/back buffers are fast-clear > resolved. > [PATCH 10/12] i965/gen7+: Resolve color buffers when necessary. > [PATCH 11/12] i965/gen7+: Disable fast color clears on shared regions. > [PATCH 12/12] i965/gen7: Enable support for fast color clears. >
Forgot to mention: this series is avaiable on branch "fast-color-clear-2" of git://github.com/stereotype441/mesa.git.
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