Commit 53503556 authored by Yifan Zhang's avatar Yifan Zhang Committed by Alex Deucher
Browse files

amd/amdkfd: correct mem limit calculation for small APUs 



Current mem limit check leaks some GTT memory (reserved_for_pt
reserved_for_ras + adev->vram_pin_size) for small APUs.

Since carveout VRAM is tunable on APUs, there are three case
regarding the carveout VRAM size relative to GTT:

1. 0 < carveout < gtt
   apu_prefer_gtt = true, is_app_apu = false

2. carveout > gtt / 2
   apu_prefer_gtt = false, is_app_apu = false

3. 0 = carveout
   apu_prefer_gtt = true, is_app_apu = true

It doesn't make sense to check below limitation in case 1
(default case, small carveout) because the values in the below
expression are mixed with carveout and gtt.

adev->kfd.vram_used[xcp_id] + vram_needed >
    vram_size - reserved_for_pt - reserved_for_ras -
    atomic64_read(&adev->vram_pin_size)

gtt: kfd.vram_used, vram_needed, vram_size
carveout: reserved_for_pt, reserved_for_ras, adev->vram_pin_size

In case 1, vram allocation will go to gtt domain, skip vram check
since ttm_mem_limit check already cover this allocation.

Signed-off-by: default avatarYifan Zhang <yifan1.zhang@amd.com>
Reviewed-by: default avatarMario Limonciello <mario.limonciello@amd.com>
Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
(cherry picked from commit fa7c99f0)
parent ce42a3b5

drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c

+32 −12
Original line number Diff line number Diff line
@@ -213,19 +213,35 @@ int amdgpu_amdkfd_reserve_mem_limit(struct amdgpu_device *adev, 
	spin_lock(&kfd_mem_limit.mem_limit_lock);



	if (kfd_mem_limit.system_mem_used + system_mem_needed >

	    kfd_mem_limit.max_system_mem_limit)

	    kfd_mem_limit.max_system_mem_limit) {

		pr_debug("Set no_system_mem_limit=1 if using shared memory\n");

		if (!no_system_mem_limit) {

			ret = -ENOMEM;

			goto release;

		}

	}



	if ((kfd_mem_limit.system_mem_used + system_mem_needed >

	     kfd_mem_limit.max_system_mem_limit && !no_system_mem_limit) ||

	    (kfd_mem_limit.ttm_mem_used + ttm_mem_needed >

	     kfd_mem_limit.max_ttm_mem_limit) ||

	    (adev && xcp_id >= 0 && adev->kfd.vram_used[xcp_id] + vram_needed >

	     vram_size - reserved_for_pt - reserved_for_ras - atomic64_read(&adev->vram_pin_size))) {

	if (kfd_mem_limit.ttm_mem_used + ttm_mem_needed >

		kfd_mem_limit.max_ttm_mem_limit) {

		ret = -ENOMEM;

		goto release;

	}



	/*if is_app_apu is false and apu_prefer_gtt is true, it is an APU with

	 * carve out < gtt. In that case, VRAM allocation will go to gtt domain, skip

	 * VRAM check since ttm_mem_limit check already cover this allocation

	 */



	if (adev && xcp_id >= 0 && (!adev->apu_prefer_gtt || adev->gmc.is_app_apu)) {

		uint64_t vram_available =

			vram_size - reserved_for_pt - reserved_for_ras -

			atomic64_read(&adev->vram_pin_size);

		if (adev->kfd.vram_used[xcp_id] + vram_needed > vram_available) {

			ret = -ENOMEM;

			goto release;

		}

	}



	/* Update memory accounting by decreasing available system

	 * memory, TTM memory and GPU memory as computed above

	 */
@@ -1626,6 +1642,10 @@ size_t amdgpu_amdkfd_get_available_memory(struct amdgpu_device *adev, 
	uint64_t vram_available, system_mem_available, ttm_mem_available;



	spin_lock(&kfd_mem_limit.mem_limit_lock);

	if (adev->apu_prefer_gtt && !adev->gmc.is_app_apu)

		vram_available = KFD_XCP_MEMORY_SIZE(adev, xcp_id)

			- adev->kfd.vram_used_aligned[xcp_id];

	else

		vram_available = KFD_XCP_MEMORY_SIZE(adev, xcp_id)

			- adev->kfd.vram_used_aligned[xcp_id]

			- atomic64_read(&adev->vram_pin_size)