[PATCH 2/3] drm/amdkfd: Set svm range max pages

[Felix Kuehling]

Am 2022-07-25 um 08:23 schrieb Philip Yang:
> This will be used to split giant svm range into smaller ranges, to
> support VRAM overcommitment by giant range and improve GPU retry fault
> recover on giant range.
>
> Signed-off-by: Philip Yang <Philip.Yang at amd.com>
> ---
>   drivers/gpu/drm/amd/amdkfd/kfd_migrate.c |  2 ++
>   drivers/gpu/drm/amd/amdkfd/kfd_svm.c     | 15 +++++++++++++++
>   drivers/gpu/drm/amd/amdkfd/kfd_svm.h     |  3 +++
>   3 files changed, 20 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c b/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
> index 9667015a6cbc..b1f87aa6138b 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
> @@ -1019,6 +1019,8 @@ int svm_migrate_init(struct amdgpu_device *adev)
>   
>   	amdgpu_amdkfd_reserve_system_mem(SVM_HMM_PAGE_STRUCT_SIZE(size));
>   
> +	svm_range_set_max_pages(adev);
> +
>   	pr_info("HMM registered %ldMB device memory\n", size >> 20);
>   
>   	return 0;
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
> index b592aee6d9d6..cf9565ddddf8 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
> @@ -46,6 +46,11 @@
>    */
>   #define AMDGPU_SVM_RANGE_RETRY_FAULT_PENDING	(2UL * NSEC_PER_MSEC)
>   
> +/* Giant svm range split into smaller ranges based on this, it is decided using
> + * minimum of all dGPU/APU 1/32 VRAM size, between 2MB to 1GB and align to 2MB.
> + */
> +uint64_t max_svm_range_pages;
> +
>   struct criu_svm_metadata {
>   	struct list_head list;
>   	struct kfd_criu_svm_range_priv_data data;
> @@ -1869,6 +1874,16 @@ static struct svm_range *svm_range_clone(struct svm_range *old)
>   
>   	return new;
>   }
> +__init void svm_range_set_max_pages(struct amdgpu_device *adev)

Why is this marked as __init? This can run much later than module init.


> +{
> +	uint64_t pages;
> +
> +	/* 1/32 VRAM size in pages */
> +	pages = adev->gmc.real_vram_size >> 17;
> +	pages = clamp(pages, 1ULL << 9, 1ULL << 18);
> +	max_svm_range_pages = min_not_zero(max_svm_range_pages, pages);
> +	max_svm_range_pages = ALIGN(max_svm_range_pages, 1ULL << 9);

I'd recommend updating max_svm_range_pages with a single WRITE_ONCE to 
avoid race conditions with GPU hot-plug.

Regards,
   Felix


> +}
>   
>   /**
>    * svm_range_add - add svm range and handle overlap
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_svm.h b/drivers/gpu/drm/amd/amdkfd/kfd_svm.h
> index eab7f6d3b13c..346a41bf8dbf 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_svm.h
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_svm.h
> @@ -204,6 +204,9 @@ void svm_range_list_lock_and_flush_work(struct svm_range_list *svms, struct mm_s
>   #define KFD_IS_SVM_API_SUPPORTED(dev) ((dev)->pgmap.type != 0)
>   
>   void svm_range_bo_unref_async(struct svm_range_bo *svm_bo);
> +
> +__init void svm_range_set_max_pages(struct amdgpu_device *adev);
> +
>   #else
>   
>   struct kfd_process;