[PATCH 2/3] drm/amdgpu: reserve at least 4MB of VRAM for page tables

[Christian König]

Oh, good point! That is probably good idea.

Christian.

Am 03.09.19 um 08:52 schrieb Zhou, David(ChunMing):
> Do you need update the vram size reported to UMD ?
>
> -David
>
> -----Original Message-----
> From: amd-gfx <amd-gfx-bounces at lists.freedesktop.org> On Behalf Of Christian König
> Sent: Monday, September 2, 2019 6:52 PM
> To: amd-gfx at lists.freedesktop.org
> Subject: [PATCH 2/3] drm/amdgpu: reserve at least 4MB of VRAM for page tables
>
> This hopefully helps reduce the contention for page tables.
>
> Signed-off-by: Christian König <christian.koenig at amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h       | 3 +++
>   drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c | 9 +++++++--
>   2 files changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
> index 2eda3a8c330d..3352a87b822e 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
> @@ -99,6 +99,9 @@ struct amdgpu_bo_list_entry;
>   #define AMDGPU_VM_FAULT_STOP_FIRST	1
>   #define AMDGPU_VM_FAULT_STOP_ALWAYS	2
>   
> +/* Reserve 4MB VRAM for page tables */
> +#define AMDGPU_VM_RESERVED_VRAM		(4ULL << 20)
> +
>   /* max number of VMHUB */
>   #define AMDGPU_MAX_VMHUBS			3
>   #define AMDGPU_GFXHUB_0				0
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> index 1150e34bc28f..59440f71d304 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> @@ -24,6 +24,7 @@
>   
>   #include <drm/drmP.h>
>   #include "amdgpu.h"
> +#include "amdgpu_vm.h"
>   
>   struct amdgpu_vram_mgr {
>   	struct drm_mm mm;
> @@ -276,7 +277,7 @@ static int amdgpu_vram_mgr_new(struct ttm_mem_type_manager *man,
>   	struct drm_mm_node *nodes;
>   	enum drm_mm_insert_mode mode;
>   	unsigned long lpfn, num_nodes, pages_per_node, pages_left;
> -	uint64_t vis_usage = 0, mem_bytes;
> +	uint64_t vis_usage = 0, mem_bytes, max_bytes;
>   	unsigned i;
>   	int r;
>   
> @@ -284,9 +285,13 @@ static int amdgpu_vram_mgr_new(struct ttm_mem_type_manager *man,
>   	if (!lpfn)
>   		lpfn = man->size;
>   
> +	max_bytes = adev->gmc.mc_vram_size;
> +	if (tbo->type != ttm_bo_type_kernel)
> +		max_bytes -= AMDGPU_VM_RESERVED_VRAM;
> +
>   	/* bail out quickly if there's likely not enough VRAM for this BO */
>   	mem_bytes = (u64)mem->num_pages << PAGE_SHIFT;
> -	if (atomic64_add_return(mem_bytes, &mgr->usage) > adev->gmc.mc_vram_size) {
> +	if (atomic64_add_return(mem_bytes, &mgr->usage) > max_bytes) {
>   		atomic64_sub(mem_bytes, &mgr->usage);
>   		mem->mm_node = NULL;
>   		return 0;