[PATCH v3 4/5] drm/amdgpu: use bulk moves for efficient VM LRU handling (v3)
Huang Rui
ray.huang at amd.com
Tue Aug 14 03:05:43 UTC 2018
On Tue, Aug 14, 2018 at 10:26:43AM +0800, Zhang, Jerry wrote:
> On 08/13/2018 05:58 PM, Huang Rui wrote:
> > 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.
> >
> > Signed-off-by: Christian König <christian.koenig at amd.com>
> > Signed-off-by: Huang Rui <ray.huang at amd.com>
> > Tested-by: Mike Lothian <mike at fireburn.co.uk>
> > ---
> > drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 73 ++++++++++++++++++++++++++--------
> > drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h | 4 ++
> > 2 files changed, 61 insertions(+), 16 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> > index 9c84770..ee1af53 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 - 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)
> > +{
> > + 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.
> > + */
> > +static void
> > +amdgpu_vm_move_to_lru_tail(struct amdgpu_device *adev, struct amdgpu_vm *vm)
> > +{
> > + struct ttm_bo_global *glob = adev->mman.bdev.glob;
> > +
> > + spin_lock(&glob->lru_lock);
> > + amdgpu_vm_move_to_lru_tail_by_list(vm, &vm->idle);
> > + amdgpu_vm_move_to_lru_tail_by_list(vm, &vm->relocated);
> > + amdgpu_vm_move_to_lru_tail_by_list(vm, &vm->moved);
>
> Moved list is working under vm->moved_lock, so we may hold that as well.
> otherwise, to use the same one.
> (not sure the detail of history about moved_lock)
We actually don't remove them from moved list, just move bo->lru to the end
of lru. So here, it doesn't need moved_lock.
>
> > + spin_unlock(&glob->lru_lock);
> > +}
> > +
> > +/**
> > * amdgpu_vm_validate_pt_bos - validate the page table BOs
> > *
> > * @adev: amdgpu device pointer
> > @@ -286,6 +333,7 @@ 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 +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);
> > }
> >
> > + validated = true;
> > if (bo->tbo.type != ttm_bo_type_kernel) {
> > spin_lock(&vm->moved_lock);
> > list_move(&bo_base->vm_status, &vm->moved);
> > @@ -312,18 +355,16 @@ 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 (!validated) {
> > + spin_lock(&glob->lru_lock);
> > + ttm_bo_bulk_move_lru_tail(&vm->lru_bulk_move);
>
> To confirm
> we only do actual bulk move when no evicted or validate failure?
>
Yes. Because if some BOs are evicted back, they will be moved to
moved/relocated list. Then we need update the positions of bulk moving.
Thanks,
Ray
> Regards,
> Jerry
>
> > + spin_unlock(&glob->lru_lock);
> > + return 0;
> > + }
> >
> > - if (!bo->parent)
> > - continue;
> > + memset(&vm->lru_bulk_move, 0, sizeof(vm->lru_bulk_move));
> >
> > - 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);
> > + amdgpu_vm_move_to_lru_tail(adev, vm);
> >
> > return r;
> > }
> > 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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