Userspace currently busywaits for fences to complete; on my workload, this
busywait consumes 10% of the available CPU time.
Provide an ioctl so that userspace can wait for an EOP interrupt that
corresponds to a previous EVENT_WRITE_EOP.
Signed-off-by: Simon Farnsworth <simon.farnsworth@xxxxxxxxxxxx>
---
I've been working on top of Jerome's tiling patches, so this doesn't apply
directly on top of current upstream kernels. I can easily rebase to another
version upon request - just point me to a git tree.
My goal is to remove the sched_yield in Mesa's r600_fence_finish given up to
date enough kernel; I hope, though, that the interface is clean enough for
other users to extend it in the future (e.g. using compute rings).
drivers/gpu/drm/radeon/radeon.h | 3 +
drivers/gpu/drm/radeon/radeon_drv.c | 3 +-
drivers/gpu/drm/radeon/radeon_fence.c | 2 +
drivers/gpu/drm/radeon/radeon_gem.c | 70 +++++++++++++++++++++++++++++++++
drivers/gpu/drm/radeon/radeon_kms.c | 1 +
include/drm/radeon_drm.h | 30 ++++++++++++++
6 files changed, 108 insertions(+), 1 deletions(-)
diff --git a/drivers/gpu/drm/radeon/radeon.h b/drivers/gpu/drm/radeon/radeon.h
index 2859406..00c187b 100644
--- a/drivers/gpu/drm/radeon/radeon.h
+++ b/drivers/gpu/drm/radeon/radeon.h
@@ -217,6 +217,7 @@ struct radeon_fence_driver {
unsigned long last_jiffies;
unsigned long last_timeout;
wait_queue_head_t queue;
+ wait_queue_head_t userspace_queue;
struct list_head created;
struct list_head emitted;
struct list_head signaled;
@@ -1348,6 +1349,8 @@ int radeon_gem_set_tiling_ioctl(struct drm_device *dev, void *data,
struct drm_file *filp);
int radeon_gem_get_tiling_ioctl(struct drm_device *dev, void *data,
struct drm_file *filp);
+int radeon_gem_wait_user_fence_ioctl(struct drm_device *dev, void *data,
+ struct drm_file *filp);
/* VRAM scratch page for HDP bug, default vram page */
struct r600_vram_scratch {
diff --git a/drivers/gpu/drm/radeon/radeon_drv.c b/drivers/gpu/drm/radeon/radeon_drv.c
index 4ae2e1d..9f82fa9 100644
--- a/drivers/gpu/drm/radeon/radeon_drv.c
+++ b/drivers/gpu/drm/radeon/radeon_drv.c
@@ -56,9 +56,10 @@
* 2.12.0 - RADEON_CS_KEEP_TILING_FLAGS
* 2.13.0 - virtual memory support
* 2.14.0 - add evergreen tiling informations
+ * 2.15.0 - gem_wait_user_fence ioctl
*/
#define KMS_DRIVER_MAJOR 2
-#define KMS_DRIVER_MINOR 14
+#define KMS_DRIVER_MINOR 15
#define KMS_DRIVER_PATCHLEVEL 0
int radeon_driver_load_kms(struct drm_device *dev, unsigned long flags);
int radeon_driver_unload_kms(struct drm_device *dev);
diff --git a/drivers/gpu/drm/radeon/radeon_fence.c b/drivers/gpu/drm/radeon/radeon_fence.c
index 64ea3dd..d86bc28 100644
--- a/drivers/gpu/drm/radeon/radeon_fence.c
+++ b/drivers/gpu/drm/radeon/radeon_fence.c
@@ -356,6 +356,7 @@ void radeon_fence_process(struct radeon_device *rdev, int ring)
if (wake) {
wake_up_all(&rdev->fence_drv[ring].queue);
}
+ wake_up_interruptible_all(&rdev->fence_drv[ring].userspace_queue);
}
int radeon_fence_count_emitted(struct radeon_device *rdev, int ring)
@@ -421,6 +422,7 @@ static void radeon_fence_driver_init_ring(struct radeon_device *rdev, int ring)
INIT_LIST_HEAD(&rdev->fence_drv[ring].emitted);
INIT_LIST_HEAD(&rdev->fence_drv[ring].signaled);
init_waitqueue_head(&rdev->fence_drv[ring].queue);
+ init_waitqueue_head(&rdev->fence_drv[ring].userspace_queue);
rdev->fence_drv[ring].initialized = false;
}
diff --git a/drivers/gpu/drm/radeon/radeon_gem.c b/drivers/gpu/drm/radeon/radeon_gem.c
index 7337850..602274f 100644
--- a/drivers/gpu/drm/radeon/radeon_gem.c
+++ b/drivers/gpu/drm/radeon/radeon_gem.c
@@ -531,3 +531,73 @@ int radeon_mode_dumb_destroy(struct drm_file *file_priv,
{
return drm_gem_handle_delete(file_priv, handle);
}
+
+int radeon_gem_wait_user_fence_ioctl(struct drm_device *dev, void *data,
+ struct drm_file *filp)
+{
+ struct drm_radeon_gem_wait_user_fence *args = data;
+ struct radeon_device *rdev = dev->dev_private;
+ struct drm_gem_object *gobj;
+ struct radeon_bo *robj;
+ void *buffer_data;
+ uint32_t *fence_data;
+ int r = 0;
+ long timeout;
+ int ring = RADEON_RING_TYPE_GFX_INDEX;
+
+ /* If you're implementing this for other rings, you'll want to share
+ code with radeon_cs_get_ring in radeon_cs.c */
+ if (args->ring != RADEON_CS_RING_GFX) {
+ return -EINVAL;
+ }
+
+ gobj = drm_gem_object_lookup(dev, filp, args->handle);
+ if (gobj == NULL) {
+ return -ENOENT;
+ }
+ robj = gem_to_radeon_bo(gobj);
+
+ if (gobj->size < args->offset) {
+ r = -EINVAL;
+ goto unreference;
+ }
+
+ r = radeon_bo_reserve(robj, true);
+ if (r) {
+ goto unreference;
+ }
+
+ r = radeon_bo_pin(robj, RADEON_GEM_DOMAIN_GTT, NULL);
+ if (r) {
+ goto unreserve;
+ }
+
+ r = radeon_bo_kmap(robj, &buffer_data);
+ if (r) {
+ goto unpin;
+ }
+
+ radeon_irq_kms_sw_irq_get(rdev, ring);
+
+ fence_data = (uint32_t*)buffer_data;
+ timeout = wait_event_interruptible_timeout(rdev->fence_drv[ring].userspace_queue,
+ fence_data[args->offset >> 2] != args->value,
+ usecs_to_jiffies(args->timeout_usec));
+
+ radeon_irq_kms_sw_irq_put(rdev, ring);
+
+ if (timeout == 0)
+ r = -ETIMEDOUT;
+ else if (timeout < 0)
+ r = timeout;
+
+ radeon_bo_kunmap(robj);
+unpin:
+ radeon_bo_unpin(robj);
+unreserve:
+ radeon_bo_unreserve(robj);
+unreference:
+ drm_gem_object_unreference_unlocked(gobj);
+
+ return r;
+}
diff --git a/drivers/gpu/drm/radeon/radeon_kms.c b/drivers/gpu/drm/radeon/radeon_kms.c
index d335288..0e552cc 100644
--- a/drivers/gpu/drm/radeon/radeon_kms.c
+++ b/drivers/gpu/drm/radeon/radeon_kms.c
@@ -496,5 +496,6 @@ struct drm_ioctl_desc radeon_ioctls_kms[] = {
DRM_IOCTL_DEF_DRV(RADEON_GEM_GET_TILING, radeon_gem_get_tiling_ioctl, DRM_AUTH|DRM_UNLOCKED),
DRM_IOCTL_DEF_DRV(RADEON_GEM_BUSY, radeon_gem_busy_ioctl, DRM_AUTH|DRM_UNLOCKED),
DRM_IOCTL_DEF_DRV(RADEON_GEM_VA, radeon_gem_va_ioctl, DRM_AUTH|DRM_UNLOCKED),
+ DRM_IOCTL_DEF_DRV(RADEON_GEM_WAIT_USER_FENCE, radeon_gem_wait_user_fence_ioctl, DRM_AUTH|DRM_UNLOCKED),
};
int radeon_max_kms_ioctl = DRM_ARRAY_SIZE(radeon_ioctls_kms);
diff --git a/include/drm/radeon_drm.h b/include/drm/radeon_drm.h
index dd2e9cf..3d4ae93 100644
--- a/include/drm/radeon_drm.h
+++ b/include/drm/radeon_drm.h
@@ -510,6 +510,7 @@ typedef struct {
#define DRM_RADEON_GEM_GET_TILING 0x29
#define DRM_RADEON_GEM_BUSY 0x2a
#define DRM_RADEON_GEM_VA 0x2b
+#define DRM_RADEON_GEM_WAIT_USER_FENCE 0x2c
#define DRM_IOCTL_RADEON_CP_INIT DRM_IOW( DRM_COMMAND_BASE + DRM_RADEON_CP_INIT, drm_radeon_init_t)
#define DRM_IOCTL_RADEON_CP_START DRM_IO( DRM_COMMAND_BASE + DRM_RADEON_CP_START)
@@ -552,6 +553,7 @@ typedef struct {
#define DRM_IOCTL_RADEON_GEM_GET_TILING DRM_IOWR(DRM_COMMAND_BASE + DRM_RADEON_GEM_GET_TILING, struct drm_radeon_gem_get_tiling)
#define DRM_IOCTL_RADEON_GEM_BUSY DRM_IOWR(DRM_COMMAND_BASE + DRM_RADEON_GEM_BUSY, struct drm_radeon_gem_busy)
#define DRM_IOCTL_RADEON_GEM_VA DRM_IOWR(DRM_COMMAND_BASE + DRM_RADEON_GEM_VA, struct drm_radeon_gem_va)
+#define DRM_IOCTL_RADEON_GEM_WAIT_USER_FENCE DRM_IOW(DRM_COMMAND_BASE + DRM_RADEON_GEM_WAIT_USER_FENCE, struct drm_radeon_gem_wait_user_fence)
typedef struct drm_radeon_init {
enum {
@@ -967,4 +969,32 @@ struct drm_radeon_info {
uint64_t value;
};
+/**
+ * struct drm_radeon_gem_wait_user_fence - DRM_RADEON_GEM_WAIT_USER_FENCE ioctl param
+ *
+ * @handle: Handle for the object that the GPU is expected to write
+ * @ring: The ring on which the fence packet was issued
+ * @offset: Offset (in bytes) within that object where the GPU is expected
+ * to write. Must be DWORD-aligned
+ * @value: The value expected if the GPU has not yet written to this location
+ * @timeout_usec: The maximum time to wait for the GPU, in microseconds
+ *
+ * The DRM_RADEON_GEM_WAIT_USER_FENCE ioctl is meant to allow userspace to
+ * avoid busy-waiting for a EVENT_WRITE_EOP packet to complete (e.g. for
+ * fence sync objects in OpenGL). It expects the EVENT_WRITE_EOP packet to
+ * have requested an interrupt on completion.
+ *
+ * The ioctl will return immediately if the value supplied is not the value
+ * found in the buffer at offset bytes in; otherwise, it will sleep for up
+ * to timeout_usec, waking up when an EVENT_WRITE_EOP packet causes an
+ * interrupt and the value in the buffer might have changed.
+ */
+struct drm_radeon_gem_wait_user_fence {
+ uint32_t handle;
+ uint32_t ring;
+ uint64_t offset;
+ uint32_t value;
+ uint64_t timeout_usec;
+};
+
#endif
--
1.7.6.4
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