[PATCH] drm/amdgpu: add flag for high priority contexts

[Mao, David]

Hi Andres,
I did not follow the previous discussion, so please remind me if my questions have been covered already~
- The priority should be the queue properties, and do we really want to expose high priority on none-compute queue?
- Another question is we may need to do per submission priority tweak if we don't reserve one compute queue ahead of time. 
From the patch, it seems you only tweak the GPU scheduler's priority, but I think it is still insufficient given we don't have OS preemption supported,
 
Thanks. 
Best Regards,
David

-----Original Message-----
From: amd-gfx [mailto:amd-gfx-bounces at lists.freedesktop.org] On Behalf Of Andres Rodriguez
Sent: Wednesday, January 4, 2017 6:55 AM
To: amd-gfx at lists.freedesktop.org
Cc: Andres Rodriguez <andresx7 at gmail.com>
Subject: [PATCH] drm/amdgpu: add flag for high priority contexts

Add a new context creation flag, AMDGPU_CTX_FLAG_HIGHPRIORITY. This flag results in the allocated context receiving a higher scheduler priority that other contexts system-wide.

Signed-off-by: Andres Rodriguez <andresx7 at gmail.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c       | 24 ++++++++++++++++++------
 drivers/gpu/drm/amd/scheduler/gpu_scheduler.h |  1 +
 include/uapi/drm/amdgpu_drm.h                 |  3 ++-
 3 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
index 400c66b..ce470e2 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
@@ -25,11 +25,17 @@
 #include <drm/drmP.h>
 #include "amdgpu.h"
 
-static int amdgpu_ctx_init(struct amdgpu_device *adev, struct amdgpu_ctx *ctx)
+static int amdgpu_ctx_init(struct amdgpu_device *adev, int priority, 
+struct amdgpu_ctx *ctx)
 {
 	unsigned i, j;
 	int r;
 
+	if (priority < 0 || priority >= AMD_SCHED_MAX_PRIORITY)
+		return -EINVAL;
+
+	if (priority == AMD_SCHED_PRIORITY_HIGH && !capable(CAP_SYS_ADMIN))
+		return -EACCES;
+
 	memset(ctx, 0, sizeof(*ctx));
 	ctx->adev = adev;
 	kref_init(&ctx->refcount);
@@ -51,7 +57,7 @@ static int amdgpu_ctx_init(struct amdgpu_device *adev, struct amdgpu_ctx *ctx)
 		struct amdgpu_ring *ring = adev->rings[i];
 		struct amd_sched_rq *rq;
 
-		rq = &ring->sched.sched_rq[AMD_SCHED_PRIORITY_NORMAL];
+		rq = &ring->sched.sched_rq[priority];
 		r = amd_sched_entity_init(&ring->sched, &ctx->rings[i].entity,
 					  rq, amdgpu_sched_jobs);
 		if (r)
@@ -90,11 +96,15 @@ static void amdgpu_ctx_fini(struct amdgpu_ctx *ctx)
 
 static int amdgpu_ctx_alloc(struct amdgpu_device *adev,
 			    struct amdgpu_fpriv *fpriv,
+			    int flags,
 			    uint32_t *id)
 {
 	struct amdgpu_ctx_mgr *mgr = &fpriv->ctx_mgr;
 	struct amdgpu_ctx *ctx;
-	int r;
+	int r, priority;
+
+	priority = flags & AMDGPU_CTX_FLAG_HIGHPRIORITY ?
+		AMD_SCHED_PRIORITY_HIGH : AMD_SCHED_PRIORITY_NORMAL;
 
 	ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
 	if (!ctx)
@@ -107,8 +117,9 @@ static int amdgpu_ctx_alloc(struct amdgpu_device *adev,
 		kfree(ctx);
 		return r;
 	}
+
 	*id = (uint32_t)r;
-	r = amdgpu_ctx_init(adev, ctx);
+	r = amdgpu_ctx_init(adev, priority, ctx);
 	if (r) {
 		idr_remove(&mgr->ctx_handles, *id);
 		*id = 0;
@@ -186,7 +197,7 @@ int amdgpu_ctx_ioctl(struct drm_device *dev, void *data,
 		     struct drm_file *filp)
 {
 	int r;
-	uint32_t id;
+	uint32_t id, flags;
 
 	union drm_amdgpu_ctx *args = data;
 	struct amdgpu_device *adev = dev->dev_private; @@ -194,10 +205,11 @@ int amdgpu_ctx_ioctl(struct drm_device *dev, void *data,
 
 	r = 0;
 	id = args->in.ctx_id;
+	flags = args->in.flags;
 
 	switch (args->in.op) {
 	case AMDGPU_CTX_OP_ALLOC_CTX:
-		r = amdgpu_ctx_alloc(adev, fpriv, &id);
+		r = amdgpu_ctx_alloc(adev, fpriv, flags, &id);
 		args->out.alloc.ctx_id = id;
 		break;
 	case AMDGPU_CTX_OP_FREE_CTX:
diff --git a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h
index d8dc681..2e458de 100644
--- a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h
+++ b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h
@@ -108,6 +108,7 @@ struct amd_sched_backend_ops {
 
 enum amd_sched_priority {
 	AMD_SCHED_PRIORITY_KERNEL = 0,
+	AMD_SCHED_PRIORITY_HIGH,
 	AMD_SCHED_PRIORITY_NORMAL,
 	AMD_SCHED_MAX_PRIORITY
 };
diff --git a/include/uapi/drm/amdgpu_drm.h b/include/uapi/drm/amdgpu_drm.h index 3961836..702332e 100644
--- a/include/uapi/drm/amdgpu_drm.h
+++ b/include/uapi/drm/amdgpu_drm.h
@@ -160,10 +160,11 @@ union drm_amdgpu_bo_list {
 /* unknown cause */
 #define AMDGPU_CTX_UNKNOWN_RESET	3
 
+#define AMDGPU_CTX_FLAG_HIGHPRIORITY	(1 << 0)
 struct drm_amdgpu_ctx_in {
 	/** AMDGPU_CTX_OP_* */
 	__u32	op;
-	/** For future use, no flags defined so far */
+	/** AMDGPU_CTX_FLAG_* */
 	__u32	flags;
 	__u32	ctx_id;
 	__u32	_pad;
--
2.7.4

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