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A mirror of the official Linux kernel repository just in case
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The BSpec says that EN_L3_RW_CCS_CACHE_FLUSH must be toggled on for manual global invalidation to take effect and actually flush device cache, however this also turns on flushing for things like pipecontrol, which occurs between submissions for compute/render. This sounds like massive overkill for our needs, where we already have the manual flushing on the display side with the global invalidation. Some observations on BMG: 1. Disabling l2 caching for host writes and stubbing out the driver global invalidation but keeping EN_L3_RW_CCS_CACHE_FLUSH enabled, has no impact on wb-transient-vs-display IGT, which makes sense since the pipecontrol is now flushing the device cache after the render copy. Without EN_L3_RW_CCS_CACHE_FLUSH the test then fails, which is also expected since device cache is now dirty and display engine can't see the writes. 2. Disabling EN_L3_RW_CCS_CACHE_FLUSH, but keeping the driver global invalidation also has no impact on wb-transient-vs-display. This suggests that the global invalidation still works as expected and is flushing the device cache without EN_L3_RW_CCS_CACHE_FLUSH turned on. With that drop EN_L3_RW_CCS_CACHE_FLUSH. This helps some workloads since we no longer flush the device cache between submissions as part of pipecontrol. Edit: We now also have clarification from HW side that BSpec was indeed wrong here. v2: - Rebase and update commit message. BSpec: 71718 Signed-off-by: Matthew Auld <matthew.auld@intel.com> Cc: Vitasta Wattal <vitasta.wattal@intel.com> Cc: Matt Roper <matthew.d.roper@intel.com> Cc: Nirmoy Das <nirmoy.das@intel.com> Reviewed-by: Nirmoy Das <nirmoy.das@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20241007074541.33937-2-matthew.auld@intel.com (cherry picked from commit 67ec9f87bd6c57db1251bb2244d242f7ca5a0b6a) [ Fix conflict due to changed xe_mmio_write32() signature ] Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com> |
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README |
Linux kernel ============ There are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. Please read Documentation/admin-guide/README.rst first. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. The formatted documentation can also be read online at: https://www.kernel.org/doc/html/latest/ There are various text files in the Documentation/ subdirectory, several of them using the reStructuredText markup notation. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.