[PATCH 4/5] drm/amdgpu: use bulk moves for efficient VM LRU handling
Christian König
christian.koenig at amd.com
Thu Aug 9 07:18:55 UTC 2018
Am 09.08.2018 um 08:18 schrieb Huang Rui:
> On Wed, Aug 08, 2018 at 06:47:49PM +0800, Christian König wrote:
>> Am 08.08.2018 um 11:59 schrieb Huang Rui:
>>> I continue to work for bulk moving that based on the proposal by Christian.
>>>
>>> Background:
>>> amdgpu driver will move all PD/PT and PerVM BOs into idle list. Then move all of
>>> them on the end of LRU list one by one. Thus, that cause so many BOs moved to
>>> the end of the LRU, and impact performance seriously.
>>>
>>> Then Christian provided a workaround to not move PD/PT BOs on LRU with below
>>> patch:
>>> "drm/amdgpu: band aid validating VM PTs"
>>> Commit 0bbf32026cf5ba41e9922b30e26e1bed1ecd38ae
>>>
>>> However, the final solution should bulk move all PD/PT and PerVM BOs on the LRU
>>> instead of one by one.
>>>
>>> Whenever amdgpu_vm_validate_pt_bos() is called and we have BOs which need to be
>>> validated we move all BOs together to the end of the LRU without dropping the
>>> lock for the LRU.
>>>
>>> While doing so we note the beginning and end of this block in the LRU list.
>>>
>>> Now when amdgpu_vm_validate_pt_bos() is called and we don't have anything to do,
>>> we don't move every BO one by one, but instead cut the LRU list into pieces so
>>> that we bulk move everything to the end in just one operation.
>>>
>>> Test data:
>>> +--------------+-----------------+-----------+---------------------------------------+
>>> | |The Talos |Clpeak(OCL)|BusSpeedReadback(OCL) |
>>> | |Principle(Vulkan)| | |
>>> +------------------------------------------------------------------------------------+
>>> | | | |0.319 ms(1k) 0.314 ms(2K) 0.308 ms(4K) |
>>> | Original | 147.7 FPS | 76.86 us |0.307 ms(8K) 0.310 ms(16K) |
>>> +------------------------------------------------------------------------------------+
>>> | Orignial + WA| | |0.254 ms(1K) 0.241 ms(2K) |
>>> |(don't move | 162.1 FPS | 42.15 us |0.230 ms(4K) 0.223 ms(8K) 0.204 ms(16K)|
>>> |PT BOs on LRU)| | | |
>>> +------------------------------------------------------------------------------------+
>>> | Bulk move | 163.1 FPS | 40.52 us |0.244 ms(1K) 0.252 ms(2K) 0.213 ms(4K) |
>>> | | | |0.214 ms(8K) 0.225 ms(16K) |
>>> +--------------+-----------------+-----------+---------------------------------------+
>>>
>>> After test them with above three benchmarks include vulkan and opencl. We can
>>> see the visible improvement than original, and even better than original with
>>> workaround.
>>>
>>> Signed-off-by: Christian König <christian.koenig at amd.com>
>>> Signed-off-by: Huang Rui <ray.huang at amd.com>
>>> ---
>>> drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 22 ++++++++++++++--------
>>> drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h | 4 ++++
>>> 2 files changed, 18 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>>> index 9c84770..eda0bb9 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>>> @@ -286,6 +286,7 @@ int amdgpu_vm_validate_pt_bos(struct amdgpu_device *adev, struct amdgpu_vm *vm,
>>> {
>>> struct ttm_bo_global *glob = adev->mman.bdev.glob;
>>> struct amdgpu_vm_bo_base *bo_base, *tmp;
>>> + bool validated = false;
>>> int r = 0;
>>>
>>> list_for_each_entry_safe(bo_base, tmp, &vm->evicted, vm_status) {
>>> @@ -295,14 +296,9 @@ int amdgpu_vm_validate_pt_bos(struct amdgpu_device *adev, struct amdgpu_vm *vm,
>>> r = validate(param, bo);
>>> if (r)
>>> break;
>>> -
>>> - spin_lock(&glob->lru_lock);
>>> - ttm_bo_move_to_lru_tail(&bo->tbo, NULL);
>>> - if (bo->shadow)
>>> - ttm_bo_move_to_lru_tail(&bo->shadow->tbo, NULL);
>>> - spin_unlock(&glob->lru_lock);
>>> }
>>>
>>> + validated = true;
>>> if (bo->tbo.type != ttm_bo_type_kernel) {
>>> spin_lock(&vm->moved_lock);
>>> list_move(&bo_base->vm_status, &vm->moved);
>>> @@ -312,6 +308,15 @@ int amdgpu_vm_validate_pt_bos(struct amdgpu_device *adev, struct amdgpu_vm *vm,
>>> }
>>> }
>>>
>>> + if (!validated) {
>>> + spin_lock(&glob->lru_lock);
>>> + ttm_bo_bulk_move_lru_tail(&vm->lru_bulk_move);
>>> + spin_unlock(&glob->lru_lock);
>>> + return 0;
>>> + }
>>> +
>>> + memset(&vm->lru_bulk_move, 0, sizeof(vm->lru_bulk_move));
>>> +
>>> spin_lock(&glob->lru_lock);
>>> list_for_each_entry(bo_base, &vm->idle, vm_status) {
>>> struct amdgpu_bo *bo = bo_base->bo;
>>> @@ -319,9 +324,10 @@ int amdgpu_vm_validate_pt_bos(struct amdgpu_device *adev, struct amdgpu_vm *vm,
>>> if (!bo->parent)
>>> continue;
>>>
>>> - ttm_bo_move_to_lru_tail(&bo->tbo, NULL);
>>> + ttm_bo_move_to_lru_tail(&bo->tbo, &vm->lru_bulk_move);
>>> if (bo->shadow)
>>> - ttm_bo_move_to_lru_tail(&bo->shadow->tbo, NULL);
>>> + ttm_bo_move_to_lru_tail(&bo->shadow->tbo,
>>> + &vm->lru_bulk_move);
>> Here is still one problem: The BOs currently evicted are not yet in the
>> idle state.
>>
>> So this must be moved to the end of the state machine, probably best if
>> we put that into a separate function.
>>
> Thanks, so the evicted BOs should be behind the BOs in idle list that in
> the group between (first, last) of bulk_move_pos, right?
The order doesn't matter.
>
> spin_lock(&glob->lru_lock);
> list_for_each_entry(bo_base, &vm->idle, vm_status) {
> struct amdgpu_bo *bo = bo_base->bo;
>
> if (!bo->parent)
> continue;
>
> ttm_bo_move_to_lru_tail(&bo->tbo, &vm->lru_bulk_move);
> if (bo->shadow)
> ttm_bo_move_to_lru_tail(&bo->shadow->tbo,
> &vm->lru_bulk_move);
> }
> list_for_each_entry_safe(bo_base, tmp, &vm->evicted, vm_status) {
That won't work. The BOs get removed from the evicted list when they are
validated.
You need to walk both the relocated as well as the moved list here.
Christian.
> struct amdgpu_bo *bo = bo_base->bo;
> if (!bo)
> continue;
>
> ttm_bo_move_to_lru_tail(&bo->tbo, &vm->lru_bulk_move);
> if (bo->shadow)
> ttm_bo_move_to_lru_tail(&bo->shadow->tbo,
> &vm->lru_bulk_move);
> }
> spin_unlock(&glob->lru_lock);
>
> Thanks,
> Ray
>
>> Regards,
>> Christian.
>>
>>> }
>>> spin_unlock(&glob->lru_lock);
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
>>> index 67a15d4..92725ac 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
>>> @@ -29,6 +29,7 @@
>>> #include <linux/rbtree.h>
>>> #include <drm/gpu_scheduler.h>
>>> #include <drm/drm_file.h>
>>> +#include <drm/ttm/ttm_bo_driver.h>
>>>
>>> #include "amdgpu_sync.h"
>>> #include "amdgpu_ring.h"
>>> @@ -226,6 +227,9 @@ struct amdgpu_vm {
>>>
>>> /* Some basic info about the task */
>>> struct amdgpu_task_info task_info;
>>> +
>>> + /* Store positions of group of BOs */
>>> + struct ttm_lru_bulk_move lru_bulk_move;
>>> };
>>>
>>> struct amdgpu_vm_manager {
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