[PATCH v4 4/5] drm/amdgpu: use bulk moves for efficient VM LRU handling (v4)
Huang Rui
ray.huang at amd.com
Wed Aug 22 03:31:02 UTC 2018
On Tue, Aug 21, 2018 at 03:54:28PM +0200, Christian König wrote:
> Am 21.08.2018 um 15:43 schrieb Huang Rui:
> >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 at amd.com>
> >>>>>Signed-off-by: Huang Rui <ray.huang at amd.com>
> >>>>>Tested-by: Mike Lothian <mike at fireburn.co.uk>
> >>>>>Tested-by: Dieter Nützel <Dieter at nuetzel-hh.de>
> >>>>>Acked-by: Chunming Zhou <david1.zhou at 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.
>
> Make sure that you don't try to move the root PD as well. E.g. test
> for bo->parent and skip if it is NULL.
>
Yes, I have skipped the root PD, but the issue is still existed.
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);
}
Let me continue to narrow down this issue.
Thanks,
Ray
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