[Intel-gfx] [PATCH v2] drm/i915: Replace kmap() with kmap_local_page()

Sumitra Sharma
2023-06-20T18:28:57Z

kmap() has been deprecated in favor of the kmap_local_page()
due to high cost, restricted mapping space, the overhead of a
global lock for synchronization, and making the process sleep
in the absence of free slots.

kmap_local_page() is faster than kmap() and offers thread-local
and CPU-local mappings, take pagefaults in a local kmap region
and preserves preemption by saving the mappings of outgoing tasks
and restoring those of the incoming one during a context switch.

The mapping is kept thread local in the function
“i915_vma_coredump_create” in i915_gpu_error.c

Therefore, replace kmap() with kmap_local_page().

Suggested-by: Ira Weiny <ira.weiny@intel.com>

Signed-off-by: Sumitra Sharma <sumitraartsy@gmail.com>
---

Changes in v2:
- Replace kmap() with kmap_local_page().
- Change commit subject and message.

drivers/gpu/drm/i915/i915_gpu_error.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c
index f020c0086fbc..bc41500eedf5 100644
--- a/drivers/gpu/drm/i915/i915_gpu_error.c
+++ b/drivers/gpu/drm/i915/i915_gpu_error.c
@@ -1164,9 +1164,9 @@ i915_vma_coredump_create(const struct intel_gt *gt,

drm_clflush_pages(&page, 1);

- s = kmap(page);
+ s = kmap_local_page(page);
ret = compress_page(compress, s, dst, false);
- kunmap(page);
+ kunmap_local(s);

drm_clflush_pages(&page, 1);

--
2.25.1