Re: [PATCH v5 1/2] drm/sched: Refactor ring mirror list handling.

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Am 21.12.18 um 21:36 schrieb Grodzovsky, Andrey:
>
> On 12/21/2018 01:37 PM, Christian König wrote:
>> Am 20.12.18 um 20:23 schrieb Andrey Grodzovsky:
>>> Decauple sched threads stop and start and ring mirror
>>> list handling from the policy of what to do about the
>>> guilty jobs.
>>> When stoppping the sched thread and detaching sched fences
>>> from non signaled HW fenes wait for all signaled HW fences
>>> to complete before rerunning the jobs.
>>>
>>> v2: Fix resubmission of guilty job into HW after refactoring.
>>>
>>> v4:
>>> Full restart for all the jobs, not only from guilty ring.
>>> Extract karma increase into standalone function.
>>>
>>> v5:
>>> Rework waiting for signaled jobs without relying on the job
>>> struct itself as those might already be freed for non 'guilty'
>>> job's schedulers.
>>> Expose karma increase to drivers.
>>>
>>> Suggested-by: Christian Koenig <Christian.Koenig@xxxxxxx>
>>> Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@xxxxxxx>
>>> ---
>>>    drivers/gpu/drm/amd/amdgpu/amdgpu_device.c |  18 +--
>>>    drivers/gpu/drm/etnaviv/etnaviv_sched.c    |  11 +-
>>>    drivers/gpu/drm/scheduler/sched_main.c     | 188
>>> +++++++++++++++++++----------
>>>    drivers/gpu/drm/v3d/v3d_sched.c            |  12 +-
>>>    include/drm/gpu_scheduler.h                |  10 +-
>>>    5 files changed, 151 insertions(+), 88 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>> index 8a078f4..a4bd2d3 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>> @@ -3298,12 +3298,10 @@ static int
>>> amdgpu_device_pre_asic_reset(struct amdgpu_device *adev,
>>>            if (!ring || !ring->sched.thread)
>>>                continue;
>>>    -        kthread_park(ring->sched.thread);
>>> +        drm_sched_stop(&ring->sched, job ? &job->base : NULL);
>>>    -        if (job && job->base.sched != &ring->sched)
>>> -            continue;
>>> -
>>> -        drm_sched_hw_job_reset(&ring->sched, job ? &job->base : NULL);
>>> +        if(job)
>>> +            drm_sched_increase_karma(&job->base);
>> Since we dropped the "job && job->base.sched != &ring->sched" check
>> above this will now increase the jobs karma multiple times.
>>
>> Maybe just move that outside of the loop.
>>
>>>              /* after all hw jobs are reset, hw fence is meaningless,
>>> so force_completion */
>>>            amdgpu_fence_driver_force_completion(ring);
>>> @@ -3454,14 +3452,10 @@ static void
>>> amdgpu_device_post_asic_reset(struct amdgpu_device *adev,
>>>            if (!ring || !ring->sched.thread)
>>>                continue;
>>>    -        /* only need recovery sched of the given job's ring
>>> -         * or all rings (in the case @job is NULL)
>>> -         * after above amdgpu_reset accomplished
>>> -         */
>>> -        if ((!job || job->base.sched == &ring->sched) &&
>>> !adev->asic_reset_res)
>>> -            drm_sched_job_recovery(&ring->sched);
>>> +        if (!adev->asic_reset_res)
>>> +            drm_sched_resubmit_jobs(&ring->sched);
>>>    -        kthread_unpark(ring->sched.thread);
>>> +        drm_sched_start(&ring->sched, !adev->asic_reset_res);
>>>        }
>>>          if (!amdgpu_device_has_dc_support(adev)) {
>>> diff --git a/drivers/gpu/drm/etnaviv/etnaviv_sched.c
>>> b/drivers/gpu/drm/etnaviv/etnaviv_sched.c
>>> index 49a6763..6f1268f 100644
>>> --- a/drivers/gpu/drm/etnaviv/etnaviv_sched.c
>>> +++ b/drivers/gpu/drm/etnaviv/etnaviv_sched.c
>>> @@ -109,16 +109,19 @@ static void etnaviv_sched_timedout_job(struct
>>> drm_sched_job *sched_job)
>>>        }
>>>          /* block scheduler */
>>> -    kthread_park(gpu->sched.thread);
>>> -    drm_sched_hw_job_reset(&gpu->sched, sched_job);
>>> +    drm_sched_stop(&gpu->sched, sched_job);
>>> +
>>> +    if(sched_job)
>>> +        drm_sched_increase_karma(sched_job);
>>>          /* get the GPU back into the init state */
>>>        etnaviv_core_dump(gpu);
>>>        etnaviv_gpu_recover_hang(gpu);
>>>    +    drm_sched_resubmit_jobs(&gpu->sched);
>>> +
>>>        /* restart scheduler after GPU is usable again */
>>> -    drm_sched_job_recovery(&gpu->sched);
>>> -    kthread_unpark(gpu->sched.thread);
>>> +    drm_sched_start(&gpu->sched, true);
>>>    }
>>>      static void etnaviv_sched_free_job(struct drm_sched_job *sched_job)
>>> diff --git a/drivers/gpu/drm/scheduler/sched_main.c
>>> b/drivers/gpu/drm/scheduler/sched_main.c
>>> index dbb6906..b5c5bee 100644
>>> --- a/drivers/gpu/drm/scheduler/sched_main.c
>>> +++ b/drivers/gpu/drm/scheduler/sched_main.c
>>> @@ -60,8 +60,6 @@
>>>      static void drm_sched_process_job(struct dma_fence *f, struct
>>> dma_fence_cb *cb);
>>>    -static void drm_sched_expel_job_unlocked(struct drm_sched_job
>>> *s_job);
>>> -
>>>    /**
>>>     * drm_sched_rq_init - initialize a given run queue struct
>>>     *
>>> @@ -335,6 +333,42 @@ static void drm_sched_job_timedout(struct
>>> work_struct *work)
>>>        spin_unlock_irqrestore(&sched->job_list_lock, flags);
>>>    }
>> Kernel doc here would be nice to have.
>>
>>> +void drm_sched_increase_karma(struct drm_sched_job *bad)
>>> +{
>>> +    int i;
>>> +    struct drm_sched_entity *tmp;
>>> +    struct drm_sched_entity *entity;
>>> +    struct drm_gpu_scheduler *sched = bad->sched;
>>> +
>>> +    /* don't increase @bad's karma if it's from KERNEL RQ,
>>> +     * because sometimes GPU hang would cause kernel jobs (like VM
>>> updating jobs)
>>> +     * corrupt but keep in mind that kernel jobs always considered
>>> good.
>>> +     */
>>> +    if (bad->s_priority != DRM_SCHED_PRIORITY_KERNEL) {
>>> +        atomic_inc(&bad->karma);
>>> +        for (i = DRM_SCHED_PRIORITY_MIN; i < DRM_SCHED_PRIORITY_KERNEL;
>>> +             i++) {
>>> +            struct drm_sched_rq *rq = &sched->sched_rq[i];
>>> +
>>> +            spin_lock(&rq->lock);
>>> +            list_for_each_entry_safe(entity, tmp, &rq->entities,
>>> list) {
>>> +                if (bad->s_fence->scheduled.context ==
>>> +                    entity->fence_context) {
>>> +                    if (atomic_read(&bad->karma) >
>>> +                        bad->sched->hang_limit)
>>> +                        if (entity->guilty)
>>> +                            atomic_set(entity->guilty, 1);
>>> +                    break;
>>> +                }
>>> +            }
>>> +            spin_unlock(&rq->lock);
>>> +            if (&entity->list != &rq->entities)
>>> +                break;
>>> +        }
>>> +    }
>>> +}
>>> +EXPORT_SYMBOL(drm_sched_increase_karma);
>>> +
>>>    /**
>>>     * drm_sched_hw_job_reset - stop the scheduler if it contains the
>>> bad job
>>>     *
>>> @@ -342,13 +376,22 @@ static void drm_sched_job_timedout(struct
>>> work_struct *work)
>>>     * @bad: bad scheduler job
>>>     *
>>>     */
>>> -void drm_sched_hw_job_reset(struct drm_gpu_scheduler *sched, struct
>>> drm_sched_job *bad)
>>> +void drm_sched_stop(struct drm_gpu_scheduler *sched, struct
>>> drm_sched_job *bad)
>>>    {
>>> -    struct drm_sched_job *s_job;
>>> -    struct drm_sched_entity *entity, *tmp;
>>> +    struct drm_sched_job *s_job, *last_job;
>>>        unsigned long flags;
>>> -    int i;
>>> +    struct dma_fence *wait_fence =  NULL;
>>> +    int r;
>>> +
>>> +    kthread_park(sched->thread);
>>>    +    /*
>>> +     * Verify all the signaled jobs in mirror list are removed from
>>> the ring
>>> +     * by waiting for their respective scheduler fences to signal.
>>> +     * Continually  repeat traversing the ring mirror list until no
>>> more signaled
>>> +     * fences are found
>>> +     */
>>> +retry_wait:
>>>        spin_lock_irqsave(&sched->job_list_lock, flags);
>>>        list_for_each_entry_reverse(s_job, &sched->ring_mirror_list,
>>> node) {
>>>            if (s_job->s_fence->parent &&
>>> @@ -357,35 +400,45 @@ void drm_sched_hw_job_reset(struct
>>> drm_gpu_scheduler *sched, struct drm_sched_jo
>>>                dma_fence_put(s_job->s_fence->parent);
>>>                s_job->s_fence->parent = NULL;
>>>                atomic_dec(&sched->hw_rq_count);
>>> +        } else {
>>> +             wait_fence = dma_fence_get(&s_job->s_fence->finished);
>>> +             last_job = s_job;
>>> +             break;
>>>            }
>>>        }
>>> -    spin_unlock_irqrestore(&sched->job_list_lock, flags);
>>>    -    if (bad && bad->s_priority != DRM_SCHED_PRIORITY_KERNEL) {
>>> -        atomic_inc(&bad->karma);
>>> -        /* don't increase @bad's karma if it's from KERNEL RQ,
>>> -         * becuase sometimes GPU hang would cause kernel jobs (like
>>> VM updating jobs)
>>> -         * corrupt but keep in mind that kernel jobs always
>>> considered good.
>>> -         */
>>> -        for (i = DRM_SCHED_PRIORITY_MIN; i <
>>> DRM_SCHED_PRIORITY_KERNEL; i++ ) {
>>> -            struct drm_sched_rq *rq = &sched->sched_rq[i];
>>> +    /* No signaled jobs in the ring, its safe to proceed to ASIC
>>> reset */
>>> +    if (!wait_fence) {
>>> +        spin_unlock_irqrestore(&sched->job_list_lock, flags);
>>> +        goto done;
>>> +    }
>>>    -            spin_lock(&rq->lock);
>>> -            list_for_each_entry_safe(entity, tmp, &rq->entities,
>>> list) {
>>> -                if (bad->s_fence->scheduled.context ==
>>> entity->fence_context) {
>>> -                    if (atomic_read(&bad->karma) >
>>> bad->sched->hang_limit)
>>> -                        if (entity->guilty)
>>> -                            atomic_set(entity->guilty, 1);
>>> -                    break;
>>> -                }
>>> -            }
>>> -            spin_unlock(&rq->lock);
>>> -            if (&entity->list != &rq->entities)
>>> -                break;
>>> +    /* Restore removed cb since removing again already removed cb is
>>> undefined */
>>> +    list_for_each_entry_reverse(s_job, &sched->ring_mirror_list,
>>> node) {
>>> +        if(s_job == last_job)
>>> +            break;
>> Need to double check after the holidays, but you should be able to use
>> list_for_each_entry_continue here.
> I think it should work - kind of traversing back on all the jobs we just
> removed their callbacks.

Wrapping your head around stuff again after the holidays sometimes shows 
new problems we have completely missed :)

Adding the callbacks again won't work because we have freed up our 
reference to the hardware fence above:
>                dma_fence_put(s_job->s_fence->parent);
>                s_job->s_fence->parent = NULL;
We need to drop this or we would never be able to re-add the fences.

But I'm still not sure if we shouldn't rely on the correct order of 
signaling and simplify this instead.

Regards,
Christian.

>
> Andrey
>
>>> +
>>> +        if (s_job->s_fence->parent) {
>>> +            r = dma_fence_add_callback(s_job->s_fence->parent,
>>> +                           &s_job->s_fence->cb,
>>> +                           drm_sched_process_job);
>>> +            if (r)
>>> +                DRM_ERROR("fence restore callback failed (%d)\n",
>>> +                                      r);
>> When you fail to add the callback this means that you need to call
>> call drm_sched_process_job manually here.
>>
>>>            }
>>>        }
>>> +    spin_unlock_irqrestore(&sched->job_list_lock, flags);
>>> +
>>> +    dma_fence_wait(wait_fence, false);
>>> +    dma_fence_put(wait_fence);
>>> +    wait_fence = NULL;
>>> +
>>> +    goto retry_wait;
>>> +
>>> +done:
>>> +    return;
>> Drop the done: label and return directly above.
>>
>> Apart from all those nit picks that starts to look like it should work,
>> Christian.
>>
>>>    }
>>> -EXPORT_SYMBOL(drm_sched_hw_job_reset);
>>> +EXPORT_SYMBOL(drm_sched_stop);
>>>      /**
>>>     * drm_sched_job_recovery - recover jobs after a reset
>>> @@ -393,33 +446,21 @@ EXPORT_SYMBOL(drm_sched_hw_job_reset);
>>>     * @sched: scheduler instance
>>>     *
>>>     */
>>> -void drm_sched_job_recovery(struct drm_gpu_scheduler *sched)
>>> +void drm_sched_start(struct drm_gpu_scheduler *sched, bool
>>> full_recovery)
>>>    {
>>>        struct drm_sched_job *s_job, *tmp;
>>> -    bool found_guilty = false;
>>>        unsigned long flags;
>>>        int r;
>>>    +    if (!full_recovery)
>>> +        goto unpark;
>>> +
>>>        spin_lock_irqsave(&sched->job_list_lock, flags);
>>>        list_for_each_entry_safe(s_job, tmp, &sched->ring_mirror_list,
>>> node) {
>>>            struct drm_sched_fence *s_fence = s_job->s_fence;
>>> -        struct dma_fence *fence;
>>> -        uint64_t guilty_context;
>>> -
>>> -        if (!found_guilty && atomic_read(&s_job->karma) >
>>> sched->hang_limit) {
>>> -            found_guilty = true;
>>> -            guilty_context = s_job->s_fence->scheduled.context;
>>> -        }
>>> -
>>> -        if (found_guilty && s_job->s_fence->scheduled.context ==
>>> guilty_context)
>>> -            dma_fence_set_error(&s_fence->finished, -ECANCELED);
>>> -
>>> -        spin_unlock_irqrestore(&sched->job_list_lock, flags);
>>> -        fence = sched->ops->run_job(s_job);
>>> -        atomic_inc(&sched->hw_rq_count);
>>> +        struct dma_fence *fence = s_job->s_fence->parent;
>>>              if (fence) {
>>> -            s_fence->parent = dma_fence_get(fence);
>>>                r = dma_fence_add_callback(fence, &s_fence->cb,
>>>                               drm_sched_process_job);
>>>                if (r == -ENOENT)
>>> @@ -427,18 +468,47 @@ void drm_sched_job_recovery(struct
>>> drm_gpu_scheduler *sched)
>>>                else if (r)
>>>                    DRM_ERROR("fence add callback failed (%d)\n",
>>>                          r);
>>> -            dma_fence_put(fence);
>>> -        } else {
>>> -            if (s_fence->finished.error < 0)
>>> -                drm_sched_expel_job_unlocked(s_job);
>>> +        } else
>>>                drm_sched_process_job(NULL, &s_fence->cb);
>>> -        }
>>> -        spin_lock_irqsave(&sched->job_list_lock, flags);
>>>        }
>>> +
>>>        drm_sched_start_timeout(sched);
>>>        spin_unlock_irqrestore(&sched->job_list_lock, flags);
>>> +
>>> +unpark:
>>> +    kthread_unpark(sched->thread);
>>> +}
>>> +EXPORT_SYMBOL(drm_sched_start);
>>> +
>>> +/**
>>> + * drm_sched_resubmit_jobs - helper to relunch job from mirror ring
>>> list
>>> + *
>>> + * @sched: scheduler instance
>>> + *
>>> + */
>>> +void drm_sched_resubmit_jobs(struct drm_gpu_scheduler *sched)
>>> +{
>>> +    struct drm_sched_job *s_job, *tmp;
>>> +    uint64_t guilty_context;
>>> +    bool found_guilty = false;
>>> +
>>> +    /*TODO DO we need spinlock here ? */
>>> +    list_for_each_entry_safe(s_job, tmp, &sched->ring_mirror_list,
>>> node) {
>>> +        struct drm_sched_fence *s_fence = s_job->s_fence;
>>> +
>>> +        if (!found_guilty && atomic_read(&s_job->karma) >
>>> sched->hang_limit) {
>>> +            found_guilty = true;
>>> +            guilty_context = s_job->s_fence->scheduled.context;
>>> +        }
>>> +
>>> +        if (found_guilty && s_job->s_fence->scheduled.context ==
>>> guilty_context)
>>> +            dma_fence_set_error(&s_fence->finished, -ECANCELED);
>>> +
>>> +        s_job->s_fence->parent = sched->ops->run_job(s_job);
>>> +        atomic_inc(&sched->hw_rq_count);
>>> +    }
>>>    }
>>> -EXPORT_SYMBOL(drm_sched_job_recovery);
>>> +EXPORT_SYMBOL(drm_sched_resubmit_jobs);
>>>      /**
>>>     * drm_sched_job_init - init a scheduler job
>>> @@ -634,26 +704,14 @@ static int drm_sched_main(void *param)
>>>                    DRM_ERROR("fence add callback failed (%d)\n",
>>>                          r);
>>>                dma_fence_put(fence);
>>> -        } else {
>>> -            if (s_fence->finished.error < 0)
>>> -                drm_sched_expel_job_unlocked(sched_job);
>>> +        } else
>>>                drm_sched_process_job(NULL, &s_fence->cb);
>>> -        }
>>>              wake_up(&sched->job_scheduled);
>>>        }
>>>        return 0;
>>>    }
>>>    -static void drm_sched_expel_job_unlocked(struct drm_sched_job *s_job)
>>> -{
>>> -    struct drm_gpu_scheduler *sched = s_job->sched;
>>> -
>>> -    spin_lock(&sched->job_list_lock);
>>> -    list_del_init(&s_job->node);
>>> -    spin_unlock(&sched->job_list_lock);
>>> -}
>>> -
>>>    /**
>>>     * drm_sched_init - Init a gpu scheduler instance
>>>     *
>>> diff --git a/drivers/gpu/drm/v3d/v3d_sched.c
>>> b/drivers/gpu/drm/v3d/v3d_sched.c
>>> index 445b2ef..f76d9ed 100644
>>> --- a/drivers/gpu/drm/v3d/v3d_sched.c
>>> +++ b/drivers/gpu/drm/v3d/v3d_sched.c
>>> @@ -178,18 +178,22 @@ v3d_job_timedout(struct drm_sched_job *sched_job)
>>>        for (q = 0; q < V3D_MAX_QUEUES; q++) {
>>>            struct drm_gpu_scheduler *sched = &v3d->queue[q].sched;
>>>    -        kthread_park(sched->thread);
>>> -        drm_sched_hw_job_reset(sched, (sched_job->sched == sched ?
>>> +        drm_sched_stop(sched, (sched_job->sched == sched ?
>>>                               sched_job : NULL));
>>> +
>>> +        if(sched_job)
>>> +            drm_sched_increase_karma(sched_job);
>>>        }
>>>          /* get the GPU back into the init state */
>>>        v3d_reset(v3d);
>>>    +    for (q = 0; q < V3D_MAX_QUEUES; q++)
>>> +        drm_sched_resubmit_jobs(sched_job->sched);
>>> +
>>>        /* Unblock schedulers and restart their jobs. */
>>>        for (q = 0; q < V3D_MAX_QUEUES; q++) {
>>> -        drm_sched_job_recovery(&v3d->queue[q].sched);
>>> -        kthread_unpark(v3d->queue[q].sched.thread);
>>> +        drm_sched_start(&v3d->queue[q].sched, true);
>>>        }
>>>          mutex_unlock(&v3d->reset_lock);
>>> diff --git a/include/drm/gpu_scheduler.h b/include/drm/gpu_scheduler.h
>>> index 47e1979..5ab2d97 100644
>>> --- a/include/drm/gpu_scheduler.h
>>> +++ b/include/drm/gpu_scheduler.h
>>> @@ -175,6 +175,7 @@ struct drm_sched_fence *to_drm_sched_fence(struct
>>> dma_fence *f);
>>>     *               finished to remove the job from the
>>>     *               @drm_gpu_scheduler.ring_mirror_list.
>>>     * @node: used to append this struct to the
>>> @drm_gpu_scheduler.ring_mirror_list.
>>> + * @finish_node: used in a list to wait on before resetting the
>>> scheduler
>>>     * @id: a unique id assigned to each job scheduled on the scheduler.
>>>     * @karma: increment on every hang caused by this job. If this
>>> exceeds the hang
>>>     *         limit of the scheduler then the job is marked guilty and
>>> will not
>>> @@ -193,6 +194,7 @@ struct drm_sched_job {
>>>        struct dma_fence_cb        finish_cb;
>>>        struct work_struct        finish_work;
>>>        struct list_head        node;
>>> +    struct list_head        finish_node;
>>>        uint64_t            id;
>>>        atomic_t            karma;
>>>        enum drm_sched_priority        s_priority;
>>> @@ -298,9 +300,11 @@ int drm_sched_job_init(struct drm_sched_job *job,
>>>                   void *owner);
>>>    void drm_sched_job_cleanup(struct drm_sched_job *job);
>>>    void drm_sched_wakeup(struct drm_gpu_scheduler *sched);
>>> -void drm_sched_hw_job_reset(struct drm_gpu_scheduler *sched,
>>> -                struct drm_sched_job *job);
>>> -void drm_sched_job_recovery(struct drm_gpu_scheduler *sched);
>>> +void drm_sched_stop(struct drm_gpu_scheduler *sched,
>>> +            struct drm_sched_job *job);
>>> +void drm_sched_start(struct drm_gpu_scheduler *sched, bool
>>> full_recovery);
>>> +void drm_sched_resubmit_jobs(struct drm_gpu_scheduler *sched);
>>> +void drm_sched_increase_karma(struct drm_sched_job *bad);
>>>    bool drm_sched_dependency_optimized(struct dma_fence* fence,
>>>                        struct drm_sched_entity *entity);
>>>    void drm_sched_fault(struct drm_gpu_scheduler *sched);
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