Am 07.03.2017 um 17:57 schrieb Alex Deucher:
On Tue, Mar 7, 2017 at 11:25 AM, Andres Rodriguez <andre...@gmail.com> wrote:

On 2017-03-07 10:19 AM, Deucher, Alexander wrote:
-----Original Message-----
From: amd-gfx [mailto:amd-gfx-boun...@lists.freedesktop.org] On Behalf
Of Christian König
Sent: Tuesday, March 07, 2017 6:00 AM
To: Andres Rodriguez; amd-gfx@lists.freedesktop.org
Subject: Re: [PATCH 18/21] drm/amdgpu: add framework for HW specific
priority settings v4

Am 07.03.2017 um 02:10 schrieb Andres Rodriguez:
Add an initial framework for changing the HW priorities of rings. The
framework allows requesting priority changes for the lifetime of an
amdgpu_job. After the job completes the priority will decay to the next
lowest priority for which a request is still valid.

A new ring function set_priority() can now be populated to take care of
the HW specific programming sequence for priority changes.

v2: set priority before emitting IB, and take a ref on amdgpu_job
v3: use AMD_SCHED_PRIORITY_* instead of AMDGPU_CTX_PRIORITY_*
v4: plug amdgpu_ring_restore_priority_cb into amdgpu_job_free_cb
v5: use atomic for tracking job priorities instead of last_job

Signed-off-by: Andres Rodriguez <andre...@gmail.com>

Two more nit picks and one real problem below.

---
   drivers/gpu/drm/amd/amdgpu/amdgpu_job.c       |  8 +++
   drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c      | 82
+++++++++++++++++++++++++++
   drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h      | 15 +++++
   drivers/gpu/drm/amd/scheduler/gpu_scheduler.h |  7 +++
   4 files changed, 112 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
b/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
index 86a1242..bd6fa0f 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
@@ -88,20 +88,21 @@ void amdgpu_job_free_resources(struct
amdgpu_job *job)
         f = job->base.s_fence ? &job->base.s_fence->finished :
job->fence;

         for (i = 0; i < job->num_ibs; ++i)
                 amdgpu_ib_free(job->adev, &job->ibs[i], f);
   }

   static void amdgpu_job_free_cb(struct amd_sched_job *s_job)
   {
         struct amdgpu_job *job = container_of(s_job, struct amdgpu_job,
base);

+       amdgpu_ring_restore_priority(job);
         dma_fence_put(job->fence);
         amdgpu_sync_free(&job->sync);
         kfree(job);
   }

   void amdgpu_job_free(struct amdgpu_job *job)
   {
         amdgpu_job_free_resources(job);

         dma_fence_put(job->fence);
@@ -162,28 +163,35 @@ static struct dma_fence *amdgpu_job_run(struct
amd_sched_job *sched_job)
         int r;

         if (!sched_job) {
                 DRM_ERROR("job is null\n");
                 return NULL;
         }
         job = to_amdgpu_job(sched_job);

         BUG_ON(amdgpu_sync_peek_fence(&job->sync, NULL));

+       r = amdgpu_ring_elevate_priority(job->ring,
+
amd_sched_get_job_priority(&job-
base),
+                                        job);
+       if (r)
+               DRM_ERROR("Failed to set job priority (%d)\n", r);
+
         trace_amdgpu_sched_run_job(job);
         r = amdgpu_ib_schedule(job->ring, job->num_ibs, job->ibs, job,
&fence);
         if (r)
                 DRM_ERROR("Error scheduling IBs (%d)\n", r);

         /* if gpu reset, hw fence will be replaced here */
         dma_fence_put(job->fence);
         job->fence = dma_fence_get(fence);
+
         amdgpu_job_free_resources(job);
         return fence;
   }

   const struct amd_sched_backend_ops amdgpu_sched_ops = {
         .dependency = amdgpu_job_dependency,
         .run_job = amdgpu_job_run,
         .timedout_job = amdgpu_job_timedout,
         .free_job = amdgpu_job_free_cb
   };
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
index d655fa4..d67dc69 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
@@ -193,20 +193,100 @@ void amdgpu_ring_commit(struct amdgpu_ring
*ring)
    */
   void amdgpu_ring_undo(struct amdgpu_ring *ring)
   {
         ring->wptr = ring->wptr_old;

         if (ring->funcs->end_use)
                 ring->funcs->end_use(ring);
   }

   /**
+ * amdgpu_ring_restore_priority - restore a ring's priority
+ *
+ * @job: job which completed execution
+ *
+ * If necessary, restore a ring's priority after a job finishes
executing
+ */
+void amdgpu_ring_restore_priority(struct amdgpu_job *job)

Only a nit pick. But just giving job_priority as parameter directly here
would bring it in line with how amdgpu_ring_elevate_priority() works.

+{
+       int i;
+       struct amdgpu_ring *ring = job->ring;
+       enum amd_sched_priority job_priority;
+
+       if (!ring->funcs->set_priority)
+               return;
+
+       job_priority = amd_sched_get_job_priority(&job->base);
+       if (atomic_dec_return(&ring->num_jobs[job_priority]) > 0)
+               return;
+
+       /* no need to restore if the job is already at the lowest
priority */
+       if (job_priority == AMD_SCHED_PRIORITY_NORMAL)
+               return;
+
+       spin_lock(&ring->priority_lock);
+       /* something higher prio is executing, no need to decay */
+       if (ring->priority < job_priority)
+               goto out_unlock;
+
+       /* decay priority to the next level with a job available */
+       for (i = job_priority; i < AMD_SCHED_MAX_PRIORITY; i++) {
+               if (i == AMD_SCHED_PRIORITY_NORMAL
+                               || atomic_read(&ring->num_jobs[i])) {
+                       ring->priority = i;
+                       ring->funcs->set_priority(ring, i);
+                       break;
+               }
+       }
+
+out_unlock:
+       spin_unlock(&ring->priority_lock);
+}
+
+/**
+ * amdgpu_ring_elevate_priority - change the ring's priority
+ *
+ * @ring: amdgpu_ring structure holding the information
+ * @priority: target priority
+ * @job: priority should remain elevated for the duration of this job
+ *
+ * Use HW specific mechanism's to elevate the ring's priority while
@job
+ * is executing. Once @job finishes executing, the ring will reset back
+ * to normal priority.
+ * Returns 0 on success, error otherwise
+ */
+int amdgpu_ring_elevate_priority(struct amdgpu_ring *ring,
+                                enum amd_sched_priority priority,
+                                struct amdgpu_job *job)

As far as I can see the job parameter is superfluous now.

+{
+       if (priority < 0 || priority >= AMD_SCHED_MAX_PRIORITY)
+               return -EINVAL;
+
+       if (!ring->funcs->set_priority)
+               return 0;
+
+       atomic_inc(&ring->num_jobs[priority]);
+
+       /* lower number means higher priority */
+       spin_lock(&ring->priority_lock);

Sorry, could be that I incorrectly suggested that. Double checking the
set_priority callback you need to take the GRBM mutex to set the
priority. Don't you?

If that's true this would be illegal cause you take a spin lock first
and then try to grab a mutex which can cause a deadlock.

BTW: Alex, Felix does anybody of hand know why the GRBM lock is a mutex
in the first place? Sounds scary to schedule while having the hardware
in a very specific state.

IIRC, Initially we only used the grbm lock during init, so a mutex seemed
sufficient.

Alex

Would converting the grbm mutex into a spinlock be a reasonable solution
here?
That's fine.  We already use spinlocks for other indirect register apertures.

Yeah, agree. I'm just not 100% sure if we don't wait for a fence or something similar nasty while holding that look.

Feel free to send a patch, but give it a round of testing with lockdep enabled. That should print nice warnings if we did something wrong here.

Christian.


Alex


-Andres


Regards,
Christian.

+       if (priority >= ring->priority)
+               goto out_unlock;
+
+       ring->priority = priority;
+       ring->funcs->set_priority(ring, priority);
+
+out_unlock:
+       spin_unlock(&ring->priority_lock);
+       return 0;
+}
+
+/**
    * amdgpu_ring_init - init driver ring struct.
    *
    * @adev: amdgpu_device pointer
    * @ring: amdgpu_ring structure holding ring information
    * @max_ndw: maximum number of dw for ring alloc
    * @nop: nop packet for this ring
    *
    * Initialize the driver information for the selected ring (all
asics).
    * Returns 0 on success, error on failure.
    */
@@ -274,20 +354,22 @@ int amdgpu_ring_init(struct amdgpu_device
*adev, struct amdgpu_ring *ring,
                                             &ring->gpu_addr,
                                             (void **)&ring->ring);
                 if (r) {
                         dev_err(adev->dev, "(%d) ring create failed\n",
r);
                         return r;
                 }
                 memset((void *)ring->ring, 0, ring->ring_size);
         }
         ring->ptr_mask = (ring->ring_size / 4) - 1;
         ring->max_dw = max_dw;
+       ring->priority = AMD_SCHED_PRIORITY_NORMAL;
+       spin_lock_init(&ring->priority_lock);
         INIT_LIST_HEAD(&ring->lru_list);
         amdgpu_ring_lru_touch(adev, ring);

         if (amdgpu_debugfs_ring_init(adev, ring)) {
                 DRM_ERROR("Failed to register debugfs file for rings
!\n");
         }
         return 0;
   }

   /**
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h
b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h
index b51bdcd..bad40f8 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h
@@ -17,20 +17,21 @@
    * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM,
DAMAGES OR
    * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
OTHERWISE,
    * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR
THE USE OR
    * OTHER DEALINGS IN THE SOFTWARE.
    *
    * Authors: Christian König
    */
   #ifndef __AMDGPU_RING_H__
   #define __AMDGPU_RING_H__

+#include <drm/amdgpu_drm.h>
   #include "gpu_scheduler.h"

   /* max number of rings */
   #define AMDGPU_MAX_RINGS              16
   #define AMDGPU_MAX_GFX_RINGS          1
   #define AMDGPU_MAX_COMPUTE_RINGS      8
   #define AMDGPU_MAX_VCE_RINGS          3

   /* some special values for the owner field */
   #define AMDGPU_FENCE_OWNER_UNDEFINED  ((void*)0ul)
@@ -45,20 +46,21 @@ enum amdgpu_ring_type {
         AMDGPU_RING_TYPE_SDMA,
         AMDGPU_RING_TYPE_UVD,
         AMDGPU_RING_TYPE_VCE,
         AMDGPU_RING_TYPE_KIQ
   };

   struct amdgpu_device;
   struct amdgpu_ring;
   struct amdgpu_ib;
   struct amdgpu_cs_parser;
+struct amdgpu_job;

   /*
    * Fences.
    */
   struct amdgpu_fence_driver {
         uint64_t                        gpu_addr;
         volatile uint32_t               *cpu_addr;
         /* sync_seq is protected by ring emission lock */
         uint32_t                        sync_seq;
         atomic_t                        last_seq;
@@ -130,20 +132,23 @@ struct amdgpu_ring_funcs {
         void (*pad_ib)(struct amdgpu_ring *ring, struct amdgpu_ib *ib);
         unsigned (*init_cond_exec)(struct amdgpu_ring *ring);
         void (*patch_cond_exec)(struct amdgpu_ring *ring, unsigned
offset);
         /* note usage for clock and power gating */
         void (*begin_use)(struct amdgpu_ring *ring);
         void (*end_use)(struct amdgpu_ring *ring);
         void (*emit_switch_buffer) (struct amdgpu_ring *ring);
         void (*emit_cntxcntl) (struct amdgpu_ring *ring, uint32_t
flags);
         void (*emit_rreg)(struct amdgpu_ring *ring, uint32_t reg);
         void (*emit_wreg)(struct amdgpu_ring *ring, uint32_t reg,
uint32_t
val);
+       /* priority functions */
+       void (*set_priority) (struct amdgpu_ring *ring,
+                             enum amd_sched_priority priority);
   };

   struct amdgpu_ring {
         struct amdgpu_device            *adev;
         const struct amdgpu_ring_funcs  *funcs;
         struct amdgpu_fence_driver      fence_drv;
         struct amd_gpu_scheduler        sched;
         struct list_head                lru_list;

         struct amdgpu_bo        *ring_obj;
@@ -164,31 +169,41 @@ struct amdgpu_ring {
         struct amdgpu_bo        *mqd_obj;
         u32                     doorbell_index;
         bool                    use_doorbell;
         unsigned                wptr_offs;
         unsigned                fence_offs;
         uint64_t                current_ctx;
         char                    name[16];
         unsigned                cond_exe_offs;
         u64                     cond_exe_gpu_addr;
         volatile u32            *cond_exe_cpu_addr;
+
+       atomic_t                num_jobs[AMD_SCHED_MAX_PRIORITY];
+       spinlock_t              priority_lock;
+       /* protected by priority_lock */
+       int                     priority;
+
   #if defined(CONFIG_DEBUG_FS)
         struct dentry *ent;
   #endif
   };

   int amdgpu_ring_is_valid_index(struct amdgpu_device *adev,
                                int hw_ip, int ring);
   int amdgpu_ring_alloc(struct amdgpu_ring *ring, unsigned ndw);
   void amdgpu_ring_insert_nop(struct amdgpu_ring *ring, uint32_t count);
   void amdgpu_ring_generic_pad_ib(struct amdgpu_ring *ring, struct
amdgpu_ib *ib);
   void amdgpu_ring_commit(struct amdgpu_ring *ring);
   void amdgpu_ring_undo(struct amdgpu_ring *ring);
+int amdgpu_ring_elevate_priority(struct amdgpu_ring *ring,
+                                enum amd_sched_priority priority,
+                                struct amdgpu_job *job);
+void amdgpu_ring_restore_priority(struct amdgpu_job *job);
   int amdgpu_ring_init(struct amdgpu_device *adev, struct amdgpu_ring
*ring,
                      unsigned ring_size, struct amdgpu_irq_src *irq_src,
                      unsigned irq_type);
   void amdgpu_ring_fini(struct amdgpu_ring *ring);
   int amdgpu_ring_lru_get(struct amdgpu_device *adev, int hw_ip,
                         struct amdgpu_ring **ring);
   void amdgpu_ring_lru_touch(struct amdgpu_device *adev, struct
amdgpu_ring *ring);

   #endif
diff --git a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h
b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h
index 2e458de..5e25674 100644
--- a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h
+++ b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h
@@ -149,11 +149,18 @@ void amd_sched_fence_slab_fini(void);
   struct amd_sched_fence *amd_sched_fence_create(
         struct amd_sched_entity *s_entity, void *owner);
   void amd_sched_fence_scheduled(struct amd_sched_fence *fence);
   void amd_sched_fence_finished(struct amd_sched_fence *fence);
   int amd_sched_job_init(struct amd_sched_job *job,
                        struct amd_gpu_scheduler *sched,
                        struct amd_sched_entity *entity,
                        void *owner);
   void amd_sched_hw_job_reset(struct amd_gpu_scheduler *sched);
   void amd_sched_job_recovery(struct amd_gpu_scheduler *sched);
+
+static inline enum amd_sched_priority
+amd_sched_get_job_priority(struct amd_sched_job *job)
+{
+       return (job->s_entity->rq - job->sched->sched_rq);
+}
+
   #endif


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