Re: [PATCH 2/2] drm/amdgpu: make an improvement on amdgpu_hmm_range_get_pages

[Christian König]

Am 09.12.23 um 00:01 schrieb James Zhu:
Needn't do schedule for each hmm_range_fault, and use cond_resched
to replace schedule.

cond_resched() is usually NAKed upstream since it is a NO-OP in most 
situations.

IIRC there was even a patch set to completely remove it.

Christian.


Signed-off-by: James Zhu <james....@amd.com>
---
  drivers/gpu/drm/amd/amdgpu/amdgpu_hmm.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_hmm.c 
b/drivers/gpu/drm/amd/amdgpu/amdgpu_hmm.c
index b24eb5821fd1..c77c4eceea46 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_hmm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_hmm.c
@@ -199,6 +199,7 @@ int amdgpu_hmm_range_get_pages(struct mmu_interval_notifier 
*notifier,
                hmm_range->notifier_seq = mmu_interval_read_begin(notifier);
                r = hmm_range_fault(hmm_range);
                if (unlikely(r)) {
+                       cond_resched();
                        /*
                         * FIXME: This timeout should encompass the retry from
                         * mmu_interval_read_retry() as well.
@@ -212,7 +213,6 @@ int amdgpu_hmm_range_get_pages(struct mmu_interval_notifier 
*notifier,
                        break;
                hmm_range->hmm_pfns += MAX_WALK_BYTE >> PAGE_SHIFT;
                hmm_range->start = hmm_range->end;
-               schedule();
        } while (hmm_range->end < end);
  
  	hmm_range->start = start;