[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 08:17:45 UTC 2018
On Tue, Aug 14, 2018 at 09:35:50AM +0200, Christian König wrote:
> Am 14.08.2018 um 09:24 schrieb Huang Rui:
> >On Tue, Aug 14, 2018 at 02:45:22PM +0800, Koenig, Christian wrote:
> >>Am 14.08.2018 um 05:05 schrieb Huang Rui:
> >>>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.
> >>Ah, crap that won't work. Jerry pointed out a quite important bug here.
> >>
> >>The moved list contains both per-VM as well as independent BOs, so
> >>walking it and moving everything on the LRU won't work as expected.
> >>
> >Our purpose is not to move the independent BOs (shared with other VM),
> >right?
> >
> >>Probably better to just walk the idle list after we are done with the
> >>state machine.
> >>
> >If we only walk the idle list here, we probably are not included all the
> >Per-VM BOs, right? Or walk the idle list after command submission.
>
> Walking the idle list after command submission. At this point all
> BOs should be on there, except for the evicted ones and we can
> handle those separately.
>
Thanks. BTW, could you please elaborate more about the state machine?
I also see it mentioned on the comments of idle list.
/* All BOs of this VM not currently in the state machine */
struct list_head idle;
Thanks,
Ray
> Regards,
> Christian.
>
> >
> >Thanks,
> >Ray
> >
> >>Christian.
> >>
> >>>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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