[RFC PATCH 0/2] Clear system pages with GPU

[Nirmoy Das]

TTM does clear on free for pooled pages and clear on alloc for
non pooled pages using CPU this can have large latency for large
buffer objects.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       GPU can clear pages much faster but mostly for larger buffers as gpu
clearing requires a gpu job submission which can make latency worse.                                                                                                                                                                                                                               XE driver on device with flat CCS clears CCS meta data with a clear                                                                                                                                                                                                                                job submission for all buffers. This series extend that clear job to
also clear system pages using GPU to improve job submission latency.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  To test the series I created a small test that tries to submit a job                                                                                                                                                                                                                               after binding various sizes of buffer.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                Without the series:                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   sudo  ~/igt-gpu-tools/build/tests/xe_exec_store --run basic-store-benchmark
IGT-Version: 1.28-g2ed908c0b (x86_64) (Linux: 6.9.0-xe+ x86_64)
Using IGT_SRANDOM=1718889799 for randomisation
Opened device: /dev/dri/card0
Starting subtest: basic-store-benchmark
Starting dynamic subtest: WC
Dynamic subtest WC: SUCCESS (0.000s)
Time taken for size SZ_4K: 4882 us
Time taken for size SZ_2M: 3679 us
Time taken for size SZ_64M: 13367 us
Time taken for size SZ_128M: 21034 us
Time taken for size SZ_256M: 32940 us
Time taken for size SZ_1G: 116261 us
Starting dynamic subtest: WB
Dynamic subtest WB: SUCCESS (0.000s)
Time taken for size SZ_4K: 5417 us
Time taken for size SZ_2M: 5711 us
Time taken for size SZ_64M: 15718 us
Time taken for size SZ_128M: 26170 us
Time taken for size SZ_256M: 50529 us
Time taken for size SZ_1G: 177933 us
Subtest basic-store-benchmark: SUCCESS (0.504s)

With the series:                                                                                                                                                                                                                                                                                   ~/igt-gpu-tools/build/tests/xe_exec_store --run basic-store-benchmark                                                                                                                                                                                                                              IGT-Version: 1.28-g2ed908c0b (x86_64) (Linux: 6.9.0-xe+ x86_64)                                                                                                                                                                                                                                    Using IGT_SRANDOM=1718889593 for randomisation                                                                                                                                                                                                                                                     Opened device: /dev/dri/card0                                                                                                                                                                                                                                                                      Starting subtest: basic-store-benchmark                                                                                                                                                                                                                                                            Starting dynamic subtest: WC                                                                                                                                                                                                                                                                       Dynamic subtest WC: SUCCESS (0.000s)                                                                                                                                                                                                                                                               Time taken for size SZ_4K: 4479 us                                                                                                                                                                                                                                                                 Time taken for size SZ_2M: 3291 us                                                                                                                                                                                                                                                                 Time taken for size SZ_64M: 6595 us                                                                                                                                                                                                                                                                Time taken for size SZ_128M: 9069 us                                                                                                                                                                                                                                                               Time taken for size SZ_256M: 12681 us                                                                                                                                                                                                                                                              Time taken for size SZ_1G: 41806 us                                                                                                                                                                                                                                                                Starting dynamic subtest: WB                                                                                                                                                                                                                                                                       Dynamic subtest WB: SUCCESS (0.000s)                                                                                                                                                                                                                                                               Time taken for size SZ_4K: 3317 us                                                                                                                                                                                                                                                                 Time taken for size SZ_2M: 6458 us                                                                                                                                                                                                                                                                 Time taken for size SZ_64M: 12802 us                                                                                                                                                                                                                                                               Time taken for size SZ_128M: 19579 us                                                                                                                                                                                                                                                              Time taken for size SZ_256M: 38768 us                                                                                                                                                                                                                                                              Time taken for size SZ_1G: 143250 us                                                                                                                                                                                                                                                               Subtest basic-store-benchmark: SUCCESS (0.328s)

Cc: Christian Koenig <christian.koenig at amd.com>
Cc: "Thomas Hellström" <thomas.hellstrom at linux.intel.com>
Cc: Matthew Auld <matthew.auld at intel.com>

Nirmoy Das (2):
  drm/ttm/pool: Introduce a way to skip clear on free
  drm/xe/lnl: Offload system clear page activity to GPU

 drivers/gpu/drm/ttm/ttm_device.c     | 42 +++++++++++++++++++++---
 drivers/gpu/drm/ttm/ttm_pool.c       | 49 +++++++++++++++++++++-------
 drivers/gpu/drm/xe/xe_bo.c           |  4 +++
 drivers/gpu/drm/xe/xe_device.c       | 38 ++++++++++++++++-----
 drivers/gpu/drm/xe/xe_device_types.h |  2 ++
 drivers/gpu/drm/xe/xe_migrate.c      |  6 ++--
 include/drm/ttm/ttm_device.h         |  8 +++++
 include/drm/ttm/ttm_pool.h           | 11 +++++++
 8 files changed, 133 insertions(+), 27 deletions(-)

-- 
2.42.0