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

[Christian König <christian.koenig@xxxxxxx>]

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.Zhu@xxxxxxx>
> ---
>   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;