Commit efe6a877 authored by Alex Deucher's avatar Alex Deucher
Browse files

drm/amdgpu: fix fairness in enforce isolation handling 



Make sure KFD gets a turn when serializing access to
the GC IP.  Currently non-KFD jobs can starve KFD if they
submit often enough.  This patch prevents that by stalling
non-KFD if its time period has elapsed.

v2: fix units
v3: check enablement properly

Acked-by: default avatarSrinivasan Shanmugam <srinivasan.shanmugam@amd.com>
Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
parent 5fd95dab

drivers/gpu/drm/amd/amdgpu/amdgpu.h

+1 −1
Original line number Diff line number Diff line
@@ -118,7 +118,7 @@ 


#define MAX_GPU_INSTANCE		64



#define GFX_SLICE_PERIOD		msecs_to_jiffies(250)

#define GFX_SLICE_PERIOD_MS		250



struct amdgpu_gpu_instance {

	struct amdgpu_device		*adev;

drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c

+51 −2
Original line number Diff line number Diff line
@@ -1752,7 +1752,7 @@ static void amdgpu_gfx_kfd_sch_ctrl(struct amdgpu_device *adev, u32 idx, 
		if (adev->gfx.kfd_sch_req_count[idx] == 0 &&

		    adev->gfx.kfd_sch_inactive[idx]) {

			schedule_delayed_work(&adev->gfx.enforce_isolation[idx].work,

					      GFX_SLICE_PERIOD);

					      msecs_to_jiffies(adev->gfx.enforce_isolation_time[idx]));

		}

	} else {

		if (adev->gfx.kfd_sch_req_count[idx] == 0) {
@@ -1807,8 +1807,9 @@ void amdgpu_gfx_enforce_isolation_handler(struct work_struct *work) 
			fences += amdgpu_fence_count_emitted(&adev->gfx.compute_ring[i]);

	}

	if (fences) {

		/* we've already had our timeslice, so let's wrap this up */

		schedule_delayed_work(&adev->gfx.enforce_isolation[idx].work,

				      GFX_SLICE_PERIOD);

				      msecs_to_jiffies(1));

	} else {

		/* Tell KFD to resume the runqueue */

		if (adev->kfd.init_complete) {
@@ -1821,6 +1822,51 @@ void amdgpu_gfx_enforce_isolation_handler(struct work_struct *work) 
	mutex_unlock(&adev->enforce_isolation_mutex);

}



static void

amdgpu_gfx_enforce_isolation_wait_for_kfd(struct amdgpu_device *adev,

					  u32 idx)

{

	unsigned long cjiffies;

	bool wait = false;



	mutex_lock(&adev->enforce_isolation_mutex);

	if (adev->enforce_isolation[idx]) {

		/* set the initial values if nothing is set */

		if (!adev->gfx.enforce_isolation_jiffies[idx]) {

			adev->gfx.enforce_isolation_jiffies[idx] = jiffies;

			adev->gfx.enforce_isolation_time[idx] =	GFX_SLICE_PERIOD_MS;

		}

		/* Make sure KFD gets a chance to run */

		if (amdgpu_amdkfd_compute_active(adev, idx)) {

			cjiffies = jiffies;

			if (time_after(cjiffies, adev->gfx.enforce_isolation_jiffies[idx])) {

				cjiffies -= adev->gfx.enforce_isolation_jiffies[idx];

				if ((jiffies_to_msecs(cjiffies) >= GFX_SLICE_PERIOD_MS)) {

					/* if our time is up, let KGD work drain before scheduling more */

					wait = true;

					/* reset the timer period */

					adev->gfx.enforce_isolation_time[idx] =	GFX_SLICE_PERIOD_MS;

				} else {

					/* set the timer period to what's left in our time slice */

					adev->gfx.enforce_isolation_time[idx] =

						GFX_SLICE_PERIOD_MS - jiffies_to_msecs(cjiffies);

				}

			} else {

				/* if jiffies wrap around we will just wait a little longer */

				adev->gfx.enforce_isolation_jiffies[idx] = jiffies;

			}

		} else {

			/* if there is no KFD work, then set the full slice period */

			adev->gfx.enforce_isolation_jiffies[idx] = jiffies;

			adev->gfx.enforce_isolation_time[idx] = GFX_SLICE_PERIOD_MS;

		}

	}

	mutex_unlock(&adev->enforce_isolation_mutex);



	if (wait)

		msleep(GFX_SLICE_PERIOD_MS);

}



void amdgpu_gfx_enforce_isolation_ring_begin_use(struct amdgpu_ring *ring)

{

	struct amdgpu_device *adev = ring->adev;
@@ -1837,6 +1883,9 @@ void amdgpu_gfx_enforce_isolation_ring_begin_use(struct amdgpu_ring *ring) 
	if (idx >= MAX_XCP)

		return;



	/* Don't submit more work until KFD has had some time */

	amdgpu_gfx_enforce_isolation_wait_for_kfd(adev, idx);



	mutex_lock(&adev->enforce_isolation_mutex);

	if (adev->enforce_isolation[idx]) {

		if (adev->kfd.init_complete)

drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.h

+2 −0
Original line number Diff line number Diff line
@@ -472,6 +472,8 @@ struct amdgpu_gfx { 
	struct mutex                    kfd_sch_mutex;

	u64				kfd_sch_req_count[MAX_XCP];

	bool				kfd_sch_inactive[MAX_XCP];

	unsigned long			enforce_isolation_jiffies[MAX_XCP];

	unsigned long			enforce_isolation_time[MAX_XCP];

};



struct amdgpu_gfx_ras_reg_entry {