Re: [PATCH v4 4/5] drm/amdgpu: use bulk moves for efficient VM LRU handling (v4)

On Mon, Aug 20, 2018 at 09:17:12PM +0800, Christian König wrote:

Am 20.08.2018 um 08:05 schrieb Huang Rui:

...

On Fri, Aug 17, 2018 at 06:38:16PM +0800, Koenig, Christian wrote:

...

Am 17.08.2018 um 12:08 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.

v2: move all BOs include idle, relocated, and moved list to the end of LRU and put them together. v3: remove unused parameter and use list_for_each_entry instead of the one with save entry. v4: move the amdgpu_vm_move_to_lru_tail after command submission, at that time, all bo will be back on idle list.

Signed-off-by: Christian König christian.koenig@amd.com Signed-off-by: Huang Rui ray.huang@amd.com Tested-by: Mike Lothian mike@fireburn.co.uk Tested-by: Dieter Nützel Dieter@nuetzel-hh.de Acked-by: Chunming Zhou david1.zhou@amd.com

---

drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c | 11 ++++++ drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 71 ++++++++++++++++++++++++++-------- drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h | 11 +++++- 3 files changed, 75 insertions(+), 18 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c index 502b94f..9fbdf02 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c @@ -1260,6 +1260,16 @@ static int amdgpu_cs_submit(struct amdgpu_cs_parser *p, return 0; }

+static void amdgpu_cs_vm_move_on_lru(struct amdgpu_device *adev,

• 		     struct amdgpu_cs_parser *p)
  

+{

• struct amdgpu_fpriv *fpriv = p->filp->driver_priv;
• struct amdgpu_vm *vm = &fpriv->vm;
• if (vm->validated)

That check belongs inside amdgpu_vm_move_to_lru_tail().

...

• amdgpu_vm_move_to_lru_tail(adev, vm);
  

+}

• int amdgpu_cs_ioctl(struct drm_device *dev, void *data, struct drm_file *filp) { struct amdgpu_device *adev = dev->dev_private;

@@ -1310,6 +1320,7 @@ int amdgpu_cs_ioctl(struct drm_device *dev, void *data, struct drm_file *filp)

r = amdgpu_cs_submit(&parser, cs);

• amdgpu_cs_vm_move_on_lru(adev, &parser); out: amdgpu_cs_parser_fini(&parser, r, reserved_buffers); return r;

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c index 9c84770..037cfbc 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c @@ -268,6 +268,53 @@ void amdgpu_vm_get_pd_bo(struct amdgpu_vm *vm, }

/**

• • amdgpu_vm_move_to_lru_tail_by_list - move one list of BOs to end of LRU
• • @vm: vm providing the BOs
• • @list: the list that stored BOs
• • Move one list of BOs to the end of LRU and update the positions.
• */

+static void +amdgpu_vm_move_to_lru_tail_by_list(struct amdgpu_vm *vm, struct list_head *list)

I don't see much of a point having a separate function for this any more.

...

+{

• struct amdgpu_vm_bo_base *bo_base;
• list_for_each_entry(bo_base, list, 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);
  

• }

+}

+/**

• • amdgpu_vm_move_to_lru_tail - move all BOs to the end of LRU
• • @adev: amdgpu device pointer
• • @vm: vm providing the BOs
• • Move all BOs to the end of LRU and remember their positions to put them
• • together.
• */

+void amdgpu_vm_move_to_lru_tail(struct amdgpu_device *adev,

• 		struct amdgpu_vm *vm)
  

+{

• struct ttm_bo_global *glob = adev->mman.bdev.glob;
• memset(&vm->lru_bulk_move, 0, sizeof(vm->lru_bulk_move));
• spin_lock(&glob->lru_lock);
• amdgpu_vm_move_to_lru_tail_by_list(vm, &vm->idle);
• spin_unlock(&glob->lru_lock);

+}

+/** * amdgpu_vm_validate_pt_bos - validate the page table BOs * * @adev: amdgpu device pointer @@ -288,6 +335,7 @@ int amdgpu_vm_validate_pt_bos(struct amdgpu_device *adev, struct amdgpu_vm *vm, struct amdgpu_vm_bo_base *bo_base, *tmp; int r = 0;

• vm->validated = false;

That won't work like this. It is perfectly possible that CS is aborted because of a signal and amdgpu_vm_move_to_lru_tail() never called.

I suggest to do "vm->validated |= !list_empty(&vm->evicted);" here and then set it to false again in amdgpu_vm_move_to_lru_tail().

And maybe we need a better name than "validated", maybe "bulk_moveable" or something like that.

Actually, "validated" is opposite to "bulk_moveable". So how about use "vm->bulk_moveable = list_empty(&vm->evicted);" here

That still won't work correct. See the validation can be interrupted.

So we need something like "vm->bulk_moveable &= list_empty(&vm->evicted);" here.

Thanks. I found if we use vm->bulk_moveable, it will have a corruption of list.

[ 2763.834228] ------------[ cut here ]------------ [ 2763.839221] list_del corruption. prev->next should be ffff9137dae028f8, but was ffffa59b82003ae0 [ 2763.848330] WARNING: CPU: 1 PID: 281 at lib/list_debug.c:53 __list_del_entry_valid+0x7c/0xa0 ... [ 2764.053257] Call Trace: [ 2764.055748] ttm_bo_del_from_lru+0x77/0xc0 [ttm] [ 2764.060437] ttm_bo_release+0x23a/0x2c0 [ttm] [ 2764.064924] amdgpu_bo_destroy+0x93/0x140 [amdgpu] [ 2764.069769] ttm_bo_release_list+0x113/0x170 [ttm] [ 2764.074695] amdgpu_bo_destroy+0x93/0x140 [amdgpu] [ 2764.079544] ttm_bo_release_list+0x113/0x170 [ttm]

However, if use vm->bulk_not_moveable (like vm->validated), the issue is gone. I didn't confirm the reason yet.

Thanks, Ray

Apart from that this now looks really good to me.

Regards, Christian.

...

Then check the flag after moving the ttm_bo_bulk_move_lru_tail() into amdgpu_vm_move_to_lru_tail() like below:

void amdgpu_vm_move_to_lru_tail(struct amdgpu_device *adev, struct amdgpu_vm *vm) { struct ttm_bo_global *glob = adev->mman.bdev.glob; struct amdgpu_vm_bo_base *bo_base;

     if (vm->bulk_moveable) {
             spin_lock(&glob->lru_lock);
             ttm_bo_bulk_move_lru_tail(&vm->lru_bulk_move);
             spin_unlock(&glob->lru_lock);
             return;
     }

     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;

             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);
     }
     spin_unlock(&glob->lru_lock);

     vm->bulk_moveable = true;

}

Thanks, Ray

...

...

list_for_each_entry_safe(bo_base, tmp, &vm->evicted, vm_status) {
	struct amdgpu_bo *bo = bo_base->bo;

@@ -295,14 +343,9 @@ 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);
  }
  
  

• vm->validated = true;
  if (bo->tbo.type != ttm_bo_type_kernel) {
  	spin_lock(&vm->moved_lock);
  	list_move(&bo_base->vm_status, &vm->moved);
  

@@ -312,20 +355,14 @@ int amdgpu_vm_validate_pt_bos(struct amdgpu_device *adev, struct amdgpu_vm *vm, } }

• 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;
  

• if (vm->validated)

• return 0;
  
  

• ttm_bo_move_to_lru_tail(&bo->tbo, NULL);
  

• if (bo->shadow)
  

• 	ttm_bo_move_to_lru_tail(&bo->shadow->tbo, NULL);
  

• }

• spin_lock(&glob->lru_lock);
• ttm_bo_bulk_move_lru_tail(&vm->lru_bulk_move); spin_unlock(&glob->lru_lock);

Probably best to move that into amdgpu_vm_move_to_lru_tail() as well.

Regards, Christian.

...

• return r;

• return 0; }

  /**

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h index 67a15d4..85d57bb 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 +227,11 @@ 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;

• /* mark whether has bo validated on evicted list */

• bool validated; };

  struct amdgpu_vm_manager {

@@ -330,8 +336,11 @@ bool amdgpu_vm_need_pipeline_sync(struct amdgpu_ring *ring, void amdgpu_vm_check_compute_bug(struct amdgpu_device *adev);

void amdgpu_vm_get_task_info(struct amdgpu_device *adev, unsigned int pasid,

• 	 struct amdgpu_task_info *task_info);
  

• 	     struct amdgpu_task_info *task_info);
  
  

  void amdgpu_vm_set_task_info(struct amdgpu_vm *vm);

+void amdgpu_vm_move_to_lru_tail(struct amdgpu_device *adev,

• 		struct amdgpu_vm *vm);
  

• #endif

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