[PATCH 2/2] drm: add tdr support for embeded hw_fence
Liu, Monk
Monk.Liu at amd.com
Fri Jul 23 08:38:27 UTC 2021
[AMD Official Use Only]
Hi Christian
How about this way:
#define AMDGPU_DMA_FENCE_FLAG_INSIDE_JOB DMA_FENCE_FLAG_USER_BITS
And we can use AMDGPU_DMA_FENCE_FLAG_INSIDE_JOB instead of DMA_FENCE_FLAG_USER_BITS everywhere
Thanks
------------------------------------------
Monk Liu | Cloud-GPU Core team
------------------------------------------
-----Original Message-----
From: Jingwen Chen <Jingwen.Chen2 at amd.com>
Sent: Friday, July 23, 2021 3:07 PM
To: Christian König <ckoenig.leichtzumerken at gmail.com>; Grodzovsky, Andrey <Andrey.Grodzovsky at amd.com>; amd-gfx at lists.freedesktop.org
Cc: Chen, Horace <Horace.Chen at amd.com>; Liu, Monk <Monk.Liu at amd.com>; Zhang, Jack (Jian) <Jack.Zhang1 at amd.com>
Subject: Re: [PATCH 2/2] drm: add tdr support for embeded hw_fence
On Fri Jul 23, 2021 at 08:33:02AM +0200, Christian König wrote:
> Am 22.07.21 um 18:47 schrieb Jingwen Chen:
> > On Thu Jul 22, 2021 at 06:24:28PM +0200, Christian König wrote:
> > > Am 22.07.21 um 16:45 schrieb Andrey Grodzovsky:
> > > > On 2021-07-22 6:45 a.m., Jingwen Chen wrote:
> > > > > On Wed Jul 21, 2021 at 12:53:51PM -0400, Andrey Grodzovsky wrote:
> > > > > > On 2021-07-20 11:13 p.m., Jingwen Chen wrote:
> > > > > > > [Why]
> > > > > > > After embeded hw_fence to amdgpu_job, we need to add tdr
> > > > > > > support for this feature.
> > > > > > >
> > > > > > > [How]
> > > > > > > 1. Add a resubmit_flag for resubmit jobs.
> > > > > > > 2. Clear job fence from RCU and force complete vm flush
> > > > > > > fences in
> > > > > > > pre_asic_reset
> > > > > > > 3. skip dma_fence_get for resubmit jobs and add a
> > > > > > > dma_fence_put
> > > > > > > for guilty jobs.
> > > > > > >
> > > > > > > Signed-off-by: Jack Zhang <Jack.Zhang1 at amd.com>
> > > > > > > Signed-off-by: Jingwen Chen <Jingwen.Chen2 at amd.com>
> > > > > > > ---
> > > > > > > drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 12
> > > > > > > +++++++++++-
> > > > > > > drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c | 16
> > > > > > > +++++++++++-----
> > > > > > > drivers/gpu/drm/amd/amdgpu/amdgpu_job.c | 4 +++-
> > > > > > > drivers/gpu/drm/scheduler/sched_main.c | 1 +
> > > > > > > include/drm/gpu_scheduler.h | 1 +
> > > > > > > 5 files changed, 27 insertions(+), 7 deletions(-)
> > > > > > >
> > > > > > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> > > > > > > b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> > > > > > > index 40461547701a..fe0237f72a09 100644
> > > > > > > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> > > > > > > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> > > > > > > @@ -4382,7 +4382,7 @@ int amdgpu_device_mode1_reset(struct
> > > > > > > amdgpu_device *adev)
> > > > > > > int amdgpu_device_pre_asic_reset(struct amdgpu_device
> > > > > > > *adev,
> > > > > > > struct amdgpu_reset_context
> > > > > > > *reset_context)
> > > > > > > {
> > > > > > > - int i, r = 0;
> > > > > > > + int i, j, r = 0;
> > > > > > > struct amdgpu_job *job = NULL;
> > > > > > > bool need_full_reset =
> > > > > > > test_bit(AMDGPU_NEED_FULL_RESET,
> > > > > > > &reset_context->flags); @@ -4406,6 +4406,16 @@ int
> > > > > > > amdgpu_device_pre_asic_reset(struct amdgpu_device *adev,
> > > > > > > if (!ring || !ring->sched.thread)
> > > > > > > continue;
> > > > > > > + /*clear job fence from fence drv to avoid
> > > > > > > +force_completion
> > > > > > > + *leave NULL and vm flush fence in fence drv */
> > > > > > > + for (j = 0; j <= ring->fence_drv.num_fences_mask;
> > > > > > > +j ++) {
> > > > > > > + struct dma_fence *old,**ptr;
> > > > > > > + ptr = &ring->fence_drv.fences[j];
> > > > > > > + old = rcu_dereference_protected(*ptr, 1);
> > > > > > > + if (old && test_bit(DMA_FENCE_FLAG_USER_BITS,
> > > > > > > &old->flags))) {
> > > > > > > + RCU_INIT_POINTER(*ptr, NULL);
> > > > > > > + }
> > > > > > Is this to avoid premature job free because of dma_fence_put
> > > > > > inside amdgpu_fence_process ?
> > > > > > I can't currently remember why but we probably want all the
> > > > > > HW fences currently in the ring to be forced signaled -
> > > > > > maybe better to test for DMA_FENCE_FLAG_USER_BITS inside
> > > > > > amdgpu_fence_process and still do the signaling but not the
> > > > > > dma_fence_put part
> > > > > >
> > > > > > Andrey
> > > > > Hi Andrey,
> > > > >
> > > > > This is to avoid signaling the same fence twice. If we still
> > > > > do the signaling, then the job in the pending list will be
> > > > > signaled first in force_completion, and later be signaled in
> > > > > resubmit. This will go to
> > > > > BUG() in amdgpu_fence_process.
> > > >
> > > > Oh, i see, how about just adding 'skip' flag to amdgpu_ring and
> > > > setting it before calling amdgpu_fence_driver_force_completion
> > > > and resetting it after, then inside
> > > > amdgpu_fence_driver_force_completion
> > > > you can just skip the signaling part with this flag for fences
> > > > with DMA_FENCE_FLAG_USER_BITS set Less lines of code at least.
> > > Still sounds quite a bit hacky.
> > >
> > > I would rather suggest to completely drop the approach with
> > > amdgpu_fence_driver_force_completion(). I could never see why we
> > > would want that in the first place.
> > >
> > > Regards,
> > > Christian.
> > >
> > Hi Christian,
> >
> > I keep the amdgpu_fence_driver_force_completion here to make sure
> > the vm flush fence is signaled and put.
> > So the key question is whether the fence of ib test should be the
> > first fence to be signaled after reset.
> > If it should be, it means not only fences with
> > DMA_FENCE_FLAG_USER_BITS but also vm flush fences should be removed
> > from RCU fence array before ib_test. Then we must do the
> > force_completion here for vm flush fence, otherwise there will be a
> > memory leak here as no one will signal and put it after we remove it from RCU.
> > If not, then the first fence to signal could be vm flush fence. And
> > I'm OK with drop amdgpu_fence_driver_force_completion here.
>
> The key problem is that amdgpu_fence_driver_force_completion() goes
> over the RCU array and signals everything there.
>
> What we should do instead is to go over the jobs and cleanup the ones
> we don't want to re-submit and keep the rest.
>
Hi Christian,
The thing is vm flush fence has no job passed to amdgpu_fence_emit, so go through the jobs cannot help find the vm flush fence. And keep the rest fences in the RCU array will lead to signaling them in the ib_test right after ASIC reset. While they will be signaled again during resubmission. What I'm doning here is just trying to cleanup the fences without a parent job and make sure the rest fences won't be signaled twice.
> And please drop any usage of DMA_FENCE_FLAG_USER_BITS. That is not
> something which should be abused for reset handling.
>
The DMA_FENCE_FLAG_USER_BITS here is to mark this fence has a parent job. If this is not a proper usage here, do you have any suggestions about how to identify whether the fence has a parent job?
Best Regards,
JingWen Chen
> Regards,
> Christian.
>
> >
> >
> > Best Regards,
> > JingWen Chen
> > > > Andrey
> > > >
> > > >
> > > > > > > + }
> > > > > > > /* after all hw jobs are reset, hw fence is
> > > > > > > meaningless, so force_completion */
> > > > > > > amdgpu_fence_driver_force_completion(ring);
> > > > > > > }
> > > > > > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c
> > > > > > > b/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c
> > > > > > > index eecf21d8ec33..815776c9a013 100644
> > > > > > > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c
> > > > > > > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c
> > > > > > > @@ -156,11 +156,17 @@ int amdgpu_fence_emit(struct
> > > > > > > amdgpu_ring *ring, struct dma_fence **f, struct amd
> > > > > > > job->ring = ring;
> > > > > > > }
> > > > > > > - seq = ++ring->fence_drv.sync_seq;
> > > > > > > - dma_fence_init(fence, &amdgpu_fence_ops,
> > > > > > > - &ring->fence_drv.lock,
> > > > > > > - adev->fence_context + ring->idx,
> > > > > > > - seq);
> > > > > > > + if (job != NULL && job->base.resubmit_flag == 1) {
> > > > > > > + /* reinit seq for resubmitted jobs */
> > > > > > > + seq = ++ring->fence_drv.sync_seq;
> > > > > > > + fence->seqno = seq;
> > > > > > > + } else {
> > > > > > > + seq = ++ring->fence_drv.sync_seq;
> > > > > > Seems like you could do the above line only once above
> > > > > > if-else as it was before
> > > > > Sure, I will modify this.
> > > > >
> > > > >
> > > > > Best Regards,
> > > > > JingWen Chen
> > > > > > > + dma_fence_init(fence, &amdgpu_fence_ops,
> > > > > > > + &ring->fence_drv.lock,
> > > > > > > + adev->fence_context + ring->idx,
> > > > > > > + seq);
> > > > > > > + }
> > > > > > > if (job != NULL) {
> > > > > > > /* mark this fence has a parent job */
> > > > > > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
> > > > > > > b/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
> > > > > > > index 7c426e225b24..d6f848adc3f4 100644
> > > > > > > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
> > > > > > > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
> > > > > > > @@ -241,6 +241,7 @@ static struct dma_fence
> > > > > > > *amdgpu_job_run(struct drm_sched_job *sched_job)
> > > > > > > dma_fence_set_error(finished, -ECANCELED);/* skip
> > > > > > > IB as well if VRAM lost */
> > > > > > > if (finished->error < 0) {
> > > > > > > + dma_fence_put(&job->hw_fence);
> > > > > > > DRM_INFO("Skip scheduling IBs!\n");
> > > > > > > } else {
> > > > > > > r = amdgpu_ib_schedule(ring, job->num_ibs, job->ibs, job,
> > > > > > > @@ -249,7 +250,8 @@ static struct dma_fence
> > > > > > > *amdgpu_job_run(struct drm_sched_job *sched_job)
> > > > > > > DRM_ERROR("Error scheduling IBs (%d)\n", r);
> > > > > > > }
> > > > > > > - dma_fence_get(fence);
> > > > > > > + if (!job->base.resubmit_flag)
> > > > > > > + dma_fence_get(fence);
> > > > > > > amdgpu_job_free_resources(job);
> > > > > > > fence = r ? ERR_PTR(r) : fence;
> > > > > > > diff --git a/drivers/gpu/drm/scheduler/sched_main.c
> > > > > > > b/drivers/gpu/drm/scheduler/sched_main.c
> > > > > > > index f4f474944169..5a36ab5aea2d 100644
> > > > > > > --- a/drivers/gpu/drm/scheduler/sched_main.c
> > > > > > > +++ b/drivers/gpu/drm/scheduler/sched_main.c
> > > > > > > @@ -544,6 +544,7 @@ void drm_sched_resubmit_jobs_ext(struct
> > > > > > > drm_gpu_scheduler *sched, int max)
> > > > > > > dma_fence_set_error(&s_fence->finished, -ECANCELED);
> > > > > > > dma_fence_put(s_job->s_fence->parent);
> > > > > > > + s_job->resubmit_flag = 1;
> > > > > > > fence = sched->ops->run_job(s_job);
> > > > > > > i++;
> > > > > > > diff --git a/include/drm/gpu_scheduler.h b/include/drm/gpu_scheduler.h
> > > > > > > index 4ea8606d91fe..06c101af1f71 100644
> > > > > > > --- a/include/drm/gpu_scheduler.h
> > > > > > > +++ b/include/drm/gpu_scheduler.h
> > > > > > > @@ -198,6 +198,7 @@ struct drm_sched_job {
> > > > > > > enum drm_sched_priority s_priority;
> > > > > > > struct drm_sched_entity *entity;
> > > > > > > struct dma_fence_cb cb;
> > > > > > > + int resubmit_flag;
> > > > > > > };
> > > > > > > static inline bool drm_sched_invalidate_job(struct
> > > > > > > drm_sched_job *s_job,
>
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