Hi,
On 03/19/2015 08:59 AM, Chris Wilson wrote:
Currently, we only track the last request globally across all engines.
This prevents us from issuing concurrent read requests on e.g. the RCS
and BCS engines (or more likely the render and media engines). Without
semaphores, we incur costly stalls as we synchronise between rings -
greatly impacting the current performance of Broadwell versus Haswell in
certain workloads (like video decode). With the introduction of
reference counted requests, it is much easier to track the last request
per ring, as well as the last global write request so that we can
optimise inter-engine read read requests (as well as better optimise
certain CPU waits).
This is quite complex and big so on first pass there will be a lot of
questions below. Especially since comments are sparse. Call it a first
pass review if that's OK with you.
v2: Fix inverted readonly condition for nonblocking waits.
v3: Handle non-continguous engine array after waits
v4: Rebase, tidy, rewrite ring list debugging
Benchmark: igt/gem_read_read_speed
hsw:gt3e (with semaphores):
Before: Time to read-read 1024k: 275.794µs
After: Time to read-read 1024k: 123.260µs
hsw:gt3e (w/o semaphores):
Before: Time to read-read 1024k: 230.433µs
After: Time to read-read 1024k: 124.593µs
bdw-u (w/o semaphores): Before After
Time to read-read 1x1: 26.274µs 10.350µs
Time to read-read 128x128: 40.097µs 21.366µs
Time to read-read 256x256: 77.087µs 42.608µs
Time to read-read 512x512: 281.999µs 181.155µs
Time to read-read 1024x1024: 1196.141µs 1118.223µs
Time to read-read 2048x2048: 5639.072µs 5225.837µs
Time to read-read 4096x4096: 22401.662µs 21137.067µs
Time to read-read 8192x8192: 89617.735µs 85637.681µs
Testcase: igt/gem_concurrent_blit (read-read and friends)
Cc: Lionel Landwerlin <lionel.g.landwerlin@xxxxxxxxxxxxxxx>
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_debugfs.c | 16 +-
drivers/gpu/drm/i915/i915_drv.h | 11 +-
drivers/gpu/drm/i915/i915_gem.c | 427 +++++++++++++++++++-------------
drivers/gpu/drm/i915/i915_gem_context.c | 2 -
drivers/gpu/drm/i915/i915_gem_debug.c | 100 +++-----
drivers/gpu/drm/i915/i915_gpu_error.c | 19 +-
drivers/gpu/drm/i915/intel_display.c | 4 +-
drivers/gpu/drm/i915/intel_ringbuffer.h | 1 +
8 files changed, 321 insertions(+), 259 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 7ef6295438e9..5cea9a9c1cb9 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -120,10 +120,13 @@ static inline const char *get_global_flag(struct drm_i915_gem_object *obj)
static void
describe_obj(struct seq_file *m, struct drm_i915_gem_object *obj)
{
+ struct drm_i915_private *dev_priv = to_i915(obj->base.dev);
+ struct intel_engine_cs *ring;
struct i915_vma *vma;
int pin_count = 0;
+ int i;
- seq_printf(m, "%pK: %s%s%s%s %8zdKiB %02x %02x %x %x %x%s%s%s",
+ seq_printf(m, "%pK: %s%s%s%s %8zdKiB %02x %02x [ ",
&obj->base,
obj->active ? "*" : " ",
get_pin_flag(obj),
@@ -131,8 +134,11 @@ describe_obj(struct seq_file *m, struct drm_i915_gem_object *obj)
get_global_flag(obj),
obj->base.size / 1024,
obj->base.read_domains,
- obj->base.write_domain,
- i915_gem_request_get_seqno(obj->last_read_req),
+ obj->base.write_domain);
+ for_each_ring(ring, dev_priv, i)
+ seq_printf(m, "%x ",
+ i915_gem_request_get_seqno(obj->last_read_req[i]));
+ seq_printf(m, "] %x %x%s%s%s",
i915_gem_request_get_seqno(obj->last_write_req),
i915_gem_request_get_seqno(obj->last_fenced_req),
i915_cache_level_str(to_i915(obj->base.dev), obj->cache_level),
@@ -169,9 +175,9 @@ describe_obj(struct seq_file *m, struct drm_i915_gem_object *obj)
*t = '\0';
seq_printf(m, " (%s mappable)", s);
}
- if (obj->last_read_req != NULL)
+ if (obj->last_write_req != NULL)
seq_printf(m, " (%s)",
- i915_gem_request_get_ring(obj->last_read_req)->name);
+ i915_gem_request_get_ring(obj->last_write_req)->name);
if (obj->frontbuffer_bits)
seq_printf(m, " (frontbuffer: 0x%03x)", obj->frontbuffer_bits);
}
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 819503e6c3d4..4436c1ca247d 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -498,7 +498,7 @@ struct drm_i915_error_state {
struct drm_i915_error_buffer {
u32 size;
u32 name;
- u32 rseqno, wseqno;
+ u32 rseqno[I915_NUM_RINGS], wseqno;
u32 gtt_offset;
u32 read_domains;
u32 write_domain;
@@ -1903,7 +1903,7 @@ struct drm_i915_gem_object {
struct drm_mm_node *stolen;
struct list_head global_list;
- struct list_head ring_list;
+ struct list_head ring_list[I915_NUM_RINGS];
/** Used in execbuf to temporarily hold a ref */
struct list_head obj_exec_link;
@@ -1914,7 +1914,7 @@ struct drm_i915_gem_object {
* rendering and so a non-zero seqno), and is not set if it i s on
* inactive (ready to be unbound) list.
*/
- unsigned int active:1;
+ unsigned int active:I915_MAX_RING_BIT;
/**
* This is set if the object has been written to since last bound
@@ -1982,7 +1982,7 @@ struct drm_i915_gem_object {
int vmapping_count;
/** Breadcrumb of last rendering to the buffer. */
- struct drm_i915_gem_request *last_read_req;
+ struct drm_i915_gem_request *last_read_req[I915_NUM_RINGS];
struct drm_i915_gem_request *last_write_req;
/** Breadcrumb of last fenced GPU access to the buffer. */
struct drm_i915_gem_request *last_fenced_req;
@@ -2120,10 +2120,11 @@ i915_gem_request_get_ring(struct drm_i915_gem_request *req)
return req ? req->ring : NULL;
}
-static inline void
+static inline struct drm_i915_gem_request *
i915_gem_request_reference(struct drm_i915_gem_request *req)
{
kref_get(&req->ref);
+ return req;
}
static inline void
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 3d6d3cec5a06..bca433a279f6 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -40,12 +40,13 @@
static void i915_gem_object_flush_gtt_write_domain(struct drm_i915_gem_object *obj);
static void i915_gem_object_flush_cpu_write_domain(struct drm_i915_gem_object *obj);
+static void
+i915_gem_object_retire__write(struct drm_i915_gem_object *obj);
+static void
+i915_gem_object_retire__read(struct drm_i915_gem_object *obj, int ring);
static __must_check int
i915_gem_object_wait_rendering(struct drm_i915_gem_object *obj,
bool readonly);
-static void
-i915_gem_object_retire(struct drm_i915_gem_object *obj);
-
static void i915_gem_write_fence(struct drm_device *dev, int reg,
struct drm_i915_gem_object *obj);
static void i915_gem_object_update_fence(struct drm_i915_gem_object *obj,
@@ -518,8 +519,6 @@ int i915_gem_obj_prepare_shmem_read(struct drm_i915_gem_object *obj,
ret = i915_gem_object_wait_rendering(obj, true);
if (ret)
return ret;
-
- i915_gem_object_retire(obj);
}
ret = i915_gem_object_get_pages(obj);
@@ -939,8 +938,6 @@ i915_gem_shmem_pwrite(struct drm_device *dev,
ret = i915_gem_object_wait_rendering(obj, false);
if (ret)
return ret;
-
- i915_gem_object_retire(obj);
}
/* Same trick applies to invalidate partially written cachelines read
* before writing. */
@@ -1372,29 +1369,8 @@ i915_wait_request(struct drm_i915_gem_request *req)
return ret;
reset_counter = atomic_read(&dev_priv->gpu_error.reset_counter);
- i915_gem_request_reference(req);
- ret = __i915_wait_request(req, reset_counter,
- interruptible, NULL, NULL);
- i915_gem_request_unreference(req);
- return ret;
-}
-
-static int
-i915_gem_object_wait_rendering__tail(struct drm_i915_gem_object *obj)
-{
- if (!obj->active)
- return 0;
-
- /* Manually manage the write flush as we may have not yet
- * retired the buffer.
- *
- * Note that the last_write_req is always the earlier of
- * the two (read/write) requests, so if we haved successfully waited,
- * we know we have passed the last write.
- */
- i915_gem_request_assign(&obj->last_write_req, NULL);
-
- return 0;
+ return __i915_wait_request(req, reset_counter,
+ interruptible, NULL, NULL);
}
Net code comments -/+ for this patch needs improvement. :) Above you
deleted a chunk but below added nothing.
I think something high level is needed to explain the active lists and
tracking etc.
/**
@@ -1405,18 +1381,39 @@ static __must_check int
i915_gem_object_wait_rendering(struct drm_i915_gem_object *obj,
bool readonly)
{
- struct drm_i915_gem_request *req;
- int ret;
+ int ret, i;
- req = readonly ? obj->last_write_req : obj->last_read_req;
- if (!req)
+ if (!obj->active)
return 0;
- ret = i915_wait_request(req);
- if (ret)
- return ret;
+ if (readonly) {
+ if (obj->last_write_req != NULL) {
+ ret = i915_wait_request(obj->last_write_req);
+ if (ret)
+ return ret;
+
+ i = obj->last_write_req->ring->id;
+ if (obj->last_read_req[i] == obj->last_write_req)
+ i915_gem_object_retire__read(obj, i);
+ else
+ i915_gem_object_retire__write(obj);
Above mentioned comments would especially help understand the ordering
rules here.
+ }
+ } else {
+ for (i = 0; i < I915_NUM_RINGS; i++) {
+ if (obj->last_read_req[i] == NULL)
+ continue;
+
+ ret = i915_wait_request(obj->last_read_req[i]);
+ if (ret)
+ return ret;
+
+ i915_gem_object_retire__read(obj, i);
+ }
I think with optimistic spinning this could end up doing num_rings spins
etc in sequence. Would it be worth smarting it up somehow?
+ BUG_ON(obj->active);
Better WARN and halt the driver indirectly if unavoidable.
+ }
+
+ return 0;
- return i915_gem_object_wait_rendering__tail(obj);
}
/* A nonblocking variant of the above wait. This is a highly dangerous routine
@@ -1427,37 +1424,71 @@ i915_gem_object_wait_rendering__nonblocking(struct drm_i915_gem_object *obj,
struct drm_i915_file_private *file_priv,
bool readonly)
{
- struct drm_i915_gem_request *req;
struct drm_device *dev = obj->base.dev;
struct drm_i915_private *dev_priv = dev->dev_private;
+ struct drm_i915_gem_request *requests[I915_NUM_RINGS];
unsigned reset_counter;
- int ret;
+ int ret, i, n = 0;
BUG_ON(!mutex_is_locked(&dev->struct_mutex));
BUG_ON(!dev_priv->mm.interruptible);
- req = readonly ? obj->last_write_req : obj->last_read_req;
- if (!req)
+ if (!obj->active)
return 0;
ret = i915_gem_check_wedge(&dev_priv->gpu_error, true);
if (ret)
return ret;
- ret = i915_gem_check_olr(req);
- if (ret)
- return ret;
-
reset_counter = atomic_read(&dev_priv->gpu_error.reset_counter);
- i915_gem_request_reference(req);
Good place for a comment: Build an array of requests to be waited upon etc..
+
+ if (readonly) {
+ struct drm_i915_gem_request *rq;
+
+ rq = obj->last_write_req;
+ if (rq == NULL)
+ return 0;
+
+ ret = i915_gem_check_olr(rq);
+ if (ret)
+ goto err;
+
+ requests[n++] = i915_gem_request_reference(rq);
+ } else {
+ for (i = 0; i < I915_NUM_RINGS; i++) {
+ struct drm_i915_gem_request *rq;
+
+ rq = obj->last_read_req[i];
+ if (rq == NULL)
+ continue;
+
+ ret = i915_gem_check_olr(rq);
+ if (ret)
+ goto err;
+
+ requests[n++] = i915_gem_request_reference(rq);
+ }
+ }
I wonder if merging the tracked requests to a single array, roughly
something like:
obj->last_req[1 + NUM_RINGS]
and:
LAST_WRITE_REQ = 0
LAST_READ_REQ(ring) = 1 + ring
Could make the above logic more compact and how would it look elsewhere
in the code? Definitely looks like it would work for the above loop:
for (i = LAST_WRITE_REQ; i <= LAST_TRACKED_REQUEST; i++) {
rq = obj->last_req[i];
if (rq == NULL && readonly)
return 0;
else if (rq == NULL)
continue;
...
requests[n++] = ...
if (readonly)
break;
}
Not sure, might not be that great idea.
+
mutex_unlock(&dev->struct_mutex);
- ret = __i915_wait_request(req, reset_counter, true, NULL, file_priv);
+ for (i = 0; ret == 0 && i < n; i++)
+ ret = __i915_wait_request(requests[i], reset_counter, true,
+ NULL, file_priv);
Another chance for more optimal "group" waiting.
mutex_lock(&dev->struct_mutex);
- i915_gem_request_unreference(req);
- if (ret)
- return ret;
- return i915_gem_object_wait_rendering__tail(obj);
+err:
+ for (i = 0; i < n; i++) {
+ if (ret == 0) {
+ int ring = requests[i]->ring->id;
+ if (obj->last_read_req[ring] == requests[i])
+ i915_gem_object_retire__read(obj, ring);
+ if (obj->last_write_req == requests[i])
+ i915_gem_object_retire__write(obj);
+ }
What if one wait succeeded and one failed, no need to update anything?
+ i915_gem_request_unreference(requests[i]);
+ }
+
+ return ret;
}
/**
@@ -2204,78 +2235,59 @@ i915_gem_object_get_pages(struct drm_i915_gem_object *obj)
return 0;
}
-static void
-i915_gem_object_move_to_active(struct drm_i915_gem_object *obj,
- struct intel_engine_cs *ring)
+void i915_vma_move_to_active(struct i915_vma *vma,
+ struct intel_engine_cs *ring)
{
- struct drm_i915_gem_request *req;
- struct intel_engine_cs *old_ring;
-
- BUG_ON(ring == NULL);
-
- req = intel_ring_get_request(ring);
- old_ring = i915_gem_request_get_ring(obj->last_read_req);
-
- if (old_ring != ring && obj->last_write_req) {
- /* Keep the request relative to the current ring */
- i915_gem_request_assign(&obj->last_write_req, req);
- }
+ struct drm_i915_gem_object *obj = vma->obj;
/* Add a reference if we're newly entering the active list. */
- if (!obj->active) {
+ if (obj->last_read_req[ring->id] == NULL && obj->active++ == 0)
drm_gem_object_reference(&obj->base);
- obj->active = 1;
- }
+ BUG_ON(obj->active == 0 || obj->active > I915_NUM_RINGS);
Maybe we need I915_WARN_AND_HALT() which would be a WARN() plus put the
driver in halted state?
- list_move_tail(&obj->ring_list, &ring->active_list);
+ list_move_tail(&obj->ring_list[ring->id], &ring->active_list);
+ i915_gem_request_assign(&obj->last_read_req[ring->id],
+ intel_ring_get_request(ring));
- i915_gem_request_assign(&obj->last_read_req, req);
+ list_move_tail(&vma->mm_list, &vma->vm->active_list);
}
-void i915_vma_move_to_active(struct i915_vma *vma,
- struct intel_engine_cs *ring)
+static void
+i915_gem_object_retire__write(struct drm_i915_gem_object *obj)
{
- list_move_tail(&vma->mm_list, &vma->vm->active_list);
- return i915_gem_object_move_to_active(vma->obj, ring);
+ BUG_ON(obj->last_write_req == NULL);
+ BUG_ON(!obj->active);
+
+ i915_gem_request_assign(&obj->last_write_req, NULL);
+
+ intel_fb_obj_flush(obj, true);
}
static void
-i915_gem_object_move_to_inactive(struct drm_i915_gem_object *obj)
+i915_gem_object_retire__read(struct drm_i915_gem_object *obj, int ring)
{
struct i915_vma *vma;
- BUG_ON(obj->base.write_domain & ~I915_GEM_GPU_DOMAINS);
+ BUG_ON(obj->last_read_req[ring] == NULL);
BUG_ON(!obj->active);
+ list_del_init(&obj->ring_list[ring]);
+ i915_gem_request_assign(&obj->last_read_req[ring], NULL);
+
+ if (obj->last_write_req && obj->last_write_req->ring->id == ring)
+ i915_gem_object_retire__write(obj);
+
+ if (--obj->active)
+ return;
+
list_for_each_entry(vma, &obj->vma_list, vma_link) {
if (!list_empty(&vma->mm_list))
list_move_tail(&vma->mm_list, &vma->vm->inactive_list);
}
- intel_fb_obj_flush(obj, true);
-
- list_del_init(&obj->ring_list);
-
- i915_gem_request_assign(&obj->last_read_req, NULL);
- i915_gem_request_assign(&obj->last_write_req, NULL);
- obj->base.write_domain = 0;
-
i915_gem_request_assign(&obj->last_fenced_req, NULL);
- obj->active = 0;
drm_gem_object_unreference(&obj->base);
-
- WARN_ON(i915_verify_lists(dev));
-}
-
-static void
-i915_gem_object_retire(struct drm_i915_gem_object *obj)
-{
- if (obj->last_read_req == NULL)
- return;
-
- if (i915_gem_request_completed(obj->last_read_req, true))
- i915_gem_object_move_to_inactive(obj);
}
static int
@@ -2583,9 +2595,9 @@ static void i915_gem_reset_ring_cleanup(struct drm_i915_private *dev_priv,
obj = list_first_entry(&ring->active_list,
struct drm_i915_gem_object,
- ring_list);
+ ring_list[ring->id]);
- i915_gem_object_move_to_inactive(obj);
+ i915_gem_object_retire__read(obj, ring->id);
}
/*
@@ -2670,6 +2682,8 @@ void i915_gem_reset(struct drm_device *dev)
i915_gem_context_reset(dev);
i915_gem_restore_fences(dev);
+
+ WARN_ON(i915_verify_lists(dev));
}
/**
@@ -2678,11 +2692,11 @@ void i915_gem_reset(struct drm_device *dev)
void
i915_gem_retire_requests_ring(struct intel_engine_cs *ring)
{
+ WARN_ON(i915_verify_lists(ring->dev));
+
if (list_empty(&ring->request_list))
return;
- WARN_ON(i915_verify_lists(ring->dev));
-
/* Retire requests first as we use it above for the early return.
* If we retire requests last, we may use a later seqno and so clear
* the requests lists without clearing the active list, leading to
@@ -2719,12 +2733,13 @@ i915_gem_retire_requests_ring(struct intel_engine_cs *ring)
obj = list_first_entry(&ring->active_list,
struct drm_i915_gem_object,
- ring_list);
+ ring_list[ring->id]);
- if (!i915_gem_request_completed(obj->last_read_req, true))
+ if (!i915_gem_request_completed(obj->last_read_req[ring->id],
+ true))
break;
- i915_gem_object_move_to_inactive(obj);
+ i915_gem_object_retire__read(obj, ring->id);
}
if (unlikely(ring->trace_irq_req &&
@@ -2813,17 +2828,23 @@ i915_gem_idle_work_handler(struct work_struct *work)
static int
i915_gem_object_flush_active(struct drm_i915_gem_object *obj)
{
- struct intel_engine_cs *ring;
- int ret;
+ int ret, i;
- if (obj->active) {
- ring = i915_gem_request_get_ring(obj->last_read_req);
+ if (!obj->active)
+ return 0;
+
+ for (i = 0; i < I915_NUM_RINGS; i++) {
+ struct drm_i915_gem_request *rq;
+
+ rq = obj->last_read_req[i];
+ if (rq == NULL)
+ continue;
- ret = i915_gem_check_olr(obj->last_read_req);
+ ret = i915_gem_check_olr(rq);
if (ret)
return ret;
- i915_gem_retire_requests_ring(ring);
+ i915_gem_retire_requests_ring(rq->ring);
}
return 0;
@@ -2857,9 +2878,10 @@ i915_gem_wait_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
struct drm_i915_private *dev_priv = dev->dev_private;
struct drm_i915_gem_wait *args = data;
struct drm_i915_gem_object *obj;
- struct drm_i915_gem_request *req;
+ struct drm_i915_gem_request *req[I915_NUM_RINGS];
unsigned reset_counter;
- int ret = 0;
+ int i, n = 0;
+ int ret;
if (args->flags != 0)
return -EINVAL;
@@ -2879,11 +2901,9 @@ i915_gem_wait_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
if (ret)
goto out;
- if (!obj->active || !obj->last_read_req)
+ if (!obj->active)
goto out;
- req = obj->last_read_req;
-
/* Do this after OLR check to make sure we make forward progress polling
* on this IOCTL with a timeout == 0 (like busy ioctl)
*/
@@ -2894,13 +2914,23 @@ i915_gem_wait_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
drm_gem_object_unreference(&obj->base);
reset_counter = atomic_read(&dev_priv->gpu_error.reset_counter);
- i915_gem_request_reference(req);
+
+ for (i = 0; i < I915_NUM_RINGS; i++) {
+ if (obj->last_read_req[i] == NULL)
+ continue;
+
+ req[n++] = i915_gem_request_reference(obj->last_read_req[i]);
+ }
+
mutex_unlock(&dev->struct_mutex);
- ret = __i915_wait_request(req, reset_counter, true,
- args->timeout_ns > 0 ? &args->timeout_ns : NULL,
- file->driver_priv);
- i915_gem_request_unreference__unlocked(req);
+ for (i = 0; i < n; i++) {
+ if (ret == 0)
+ ret = __i915_wait_request(req[i], reset_counter, true,
+ args->timeout_ns > 0 ? &args->timeout_ns : NULL,
+ file->driver_priv);
+ i915_gem_request_unreference__unlocked(req[i]);
+ }
return ret;
out:
@@ -2909,6 +2939,62 @@ out:
return ret;
}
+static int
+__i915_gem_object_sync(struct drm_i915_gem_object *obj,
+ struct intel_engine_cs *to,
+ struct drm_i915_gem_request *rq)
+{
+ struct intel_engine_cs *from;
+ int ret;
+
+ if (rq == NULL)
+ return 0;
+
+ from = i915_gem_request_get_ring(rq);
+ if (to == from)
+ return 0;
+
+ if (i915_gem_request_completed(rq, true))
+ return 0;
+
+ ret = i915_gem_check_olr(rq);
+ if (ret)
+ return ret;
+
+ if (!i915_semaphore_is_enabled(obj->base.dev)) {
+ ret = __i915_wait_request(rq,
+ atomic_read(&to_i915(obj->base.dev)->gpu_error.reset_counter),
+ to_i915(obj->base.dev)->mm.interruptible, NULL, NULL);
+ if (ret)
+ return ret;
+
+ if (obj->last_read_req[from->id] == rq)
+ i915_gem_object_retire__read(obj, from->id);
+ if (obj->last_write_req == rq)
+ i915_gem_object_retire__write(obj);
Retiring reads implies retiring writes on a ring so is this needed?
+ } else {
+ int idx = intel_ring_sync_index(from, to);
+ u32 seqno = i915_gem_request_get_seqno(rq);
+
+ if (seqno <= from->semaphore.sync_seqno[idx])
+ return 0;
+
+ trace_i915_gem_ring_sync_to(from, to, rq);
+ ret = to->semaphore.sync_to(to, from, seqno);
+ if (ret)
+ return ret;
+
+ /* We use last_read_req because sync_to()
+ * might have just caused seqno wrap under
+ * the radar.
+ */
+ from->semaphore.sync_seqno[idx] =
+ i915_gem_request_get_seqno(obj->last_read_req[from->id]);
+ }
+
+ return 0;
+}
+
/**
* i915_gem_object_sync - sync an object to a ring.
*
@@ -2917,7 +3003,17 @@ out:
*
* This code is meant to abstract object synchronization with the GPU.
* Calling with NULL implies synchronizing the object with the CPU
- * rather than a particular GPU ring.
+ * rather than a particular GPU ring. Conceptually we serialise writes
+ * between engines inside the GPU. We only allow on engine to write
+ * into a buffer at any time, but multiple readers. To ensure each has
+ * a coherent view of memory, we must:
+ *
+ * - If there is an outstanding write request to the object, the new
+ * request must wait for it to complete (either CPU or in hw, requests
+ * on the same ring will be naturally ordered).
+ *
+ * - If we are a write request (pending_write_domain is set), the new
+ * request must wait for outstanding read requests to complete.
*
* Returns 0 if successful, else propagates up the lower layer error.
*/
@@ -2925,39 +3021,25 @@ int
i915_gem_object_sync(struct drm_i915_gem_object *obj,
struct intel_engine_cs *to)
{
- struct intel_engine_cs *from;
- u32 seqno;
- int ret, idx;
-
- from = i915_gem_request_get_ring(obj->last_read_req);
-
- if (from == NULL || to == from)
- return 0;
-
- if (to == NULL || !i915_semaphore_is_enabled(obj->base.dev))
- return i915_gem_object_wait_rendering(obj, false);
-
- idx = intel_ring_sync_index(from, to);
+ const bool readonly = obj->base.pending_write_domain == 0;
+ int ret, i;
- seqno = i915_gem_request_get_seqno(obj->last_read_req);
- /* Optimization: Avoid semaphore sync when we are sure we already
- * waited for an object with higher seqno */
- if (seqno <= from->semaphore.sync_seqno[idx])
+ if (!obj->active)
return 0;
- ret = i915_gem_check_olr(obj->last_read_req);
- if (ret)
- return ret;
-
- trace_i915_gem_ring_sync_to(from, to, obj->last_read_req);
- ret = to->semaphore.sync_to(to, from, seqno);
- if (!ret)
- /* We use last_read_req because sync_to()
- * might have just caused seqno wrap under
- * the radar.
- */
- from->semaphore.sync_seqno[idx] =
- i915_gem_request_get_seqno(obj->last_read_req);
+ if (to == NULL) {
+ ret = i915_gem_object_wait_rendering(obj, readonly);
+ } else if (readonly) {
+ ret = __i915_gem_object_sync(obj, to,
+ obj->last_write_req);
+ } else {
+ for (i = 0; i < I915_NUM_RINGS; i++) {
+ ret = __i915_gem_object_sync(obj, to,
+ obj->last_read_req[i]);
Here I think is another opportunity to wait for all of them at once. Via
a __i915_gem_object_sync helper which would take an array, or a
ring/request mask. Not sure if it would be worth it though.
+ if (ret)
+ break;
+ }
+ }
return ret;
}
@@ -3044,10 +3126,6 @@ int i915_vma_unbind(struct i915_vma *vma)
/* Since the unbound list is global, only move to that list if
* no more VMAs exist. */
if (list_empty(&obj->vma_list)) {
- /* Throw away the active reference before
- * moving to the unbound list. */
- i915_gem_object_retire(obj);
-
i915_gem_gtt_finish_object(obj);
list_move_tail(&obj->global_list, &dev_priv->mm.unbound_list);
}
@@ -3678,8 +3756,6 @@ i915_gem_object_set_to_gtt_domain(struct drm_i915_gem_object *obj, bool write)
if (ret)
return ret;
- i915_gem_object_retire(obj);
-
/* Flush and acquire obj->pages so that we are coherent through
* direct access in memory with previous cached writes through
* shmemfs and that our cache domain tracking remains valid.
@@ -3904,11 +3980,9 @@ i915_gem_object_pin_to_display_plane(struct drm_i915_gem_object *obj,
bool was_pin_display;
int ret;
- if (pipelined != i915_gem_request_get_ring(obj->last_read_req)) {
- ret = i915_gem_object_sync(obj, pipelined);
- if (ret)
- return ret;
- }
+ ret = i915_gem_object_sync(obj, pipelined);
+ if (ret)
+ return ret;
/* Mark the pin_display early so that we account for the
* display coherency whilst setting up the cache domains.
@@ -4004,7 +4078,6 @@ i915_gem_object_set_to_cpu_domain(struct drm_i915_gem_object *obj, bool write)
if (ret)
return ret;
- i915_gem_object_retire(obj);
i915_gem_object_flush_gtt_write_domain(obj);
old_write_domain = obj->base.write_domain;
@@ -4297,15 +4370,24 @@ i915_gem_busy_ioctl(struct drm_device *dev, void *data,
* necessary flushes here.
*/
ret = i915_gem_object_flush_active(obj);
+ if (ret)
+ goto unref;
+
+ args->busy = 0;
+ if (obj->active) {
+ int i;
- args->busy = obj->active;
- if (obj->last_read_req) {
- struct intel_engine_cs *ring;
BUILD_BUG_ON(I915_NUM_RINGS > 16);
- ring = i915_gem_request_get_ring(obj->last_read_req);
- args->busy |= intel_ring_flag(ring) << 16;
+
+ for (i = 0; i < I915_NUM_RINGS; i++) {
+ if (obj->last_read_req[i] == NULL)
+ continue;
+
+ args->busy |= 1 << (16 + i) | 1;
Doesn't look like equivalent bits will be set? What is the "| 1" at the
end for?
+ }
}
+unref:
drm_gem_object_unreference(&obj->base);
unlock:
mutex_unlock(&dev->struct_mutex);
@@ -4379,8 +4461,11 @@ unlock:
void i915_gem_object_init(struct drm_i915_gem_object *obj,
const struct drm_i915_gem_object_ops *ops)
{
+ int i;
+
INIT_LIST_HEAD(&obj->global_list);
- INIT_LIST_HEAD(&obj->ring_list);
+ for (i = 0; i < I915_NUM_RINGS; i++)
+ INIT_LIST_HEAD(&obj->ring_list[i]);
INIT_LIST_HEAD(&obj->obj_exec_link);
INIT_LIST_HEAD(&obj->vma_list);
INIT_LIST_HEAD(&obj->batch_pool_link);
diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
index 70346b0028f9..31826e7e904c 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -673,8 +673,6 @@ static int do_switch(struct intel_engine_cs *ring,
* swapped, but there is no way to do that yet.
*/
from->legacy_hw_ctx.rcs_state->dirty = 1;
- BUG_ON(i915_gem_request_get_ring(
- from->legacy_hw_ctx.rcs_state->last_read_req) != ring);
/* obj is kept alive until the next request by its active ref */
i915_gem_object_ggtt_unpin(from->legacy_hw_ctx.rcs_state);
diff --git a/drivers/gpu/drm/i915/i915_gem_debug.c b/drivers/gpu/drm/i915/i915_gem_debug.c
index f462d1b51d97..f1cdddada369 100644
--- a/drivers/gpu/drm/i915/i915_gem_debug.c
+++ b/drivers/gpu/drm/i915/i915_gem_debug.c
@@ -34,82 +34,46 @@ int
i915_verify_lists(struct drm_device *dev)
{
static int warned;
- struct drm_i915_private *dev_priv = dev->dev_private;
+ struct drm_i915_private *dev_priv = to_i915(dev);
struct drm_i915_gem_object *obj;
+ struct intel_engine_cs *ring;
int err = 0;
+ int i;
if (warned)
return 0;
- list_for_each_entry(obj, &dev_priv->render_ring.active_list, list) {
- if (obj->base.dev != dev ||
- !atomic_read(&obj->base.refcount.refcount)) {
- DRM_ERROR("freed render active %p\n", obj);
- err++;
- break;
- } else if (!obj->active ||
- (obj->base.read_domains & I915_GEM_GPU_DOMAINS) == 0) {
- DRM_ERROR("invalid render active %p (a %d r %x)\n",
- obj,
- obj->active,
- obj->base.read_domains);
- err++;
- } else if (obj->base.write_domain && list_empty(&obj->gpu_write_list)) {
- DRM_ERROR("invalid render active %p (w %x, gwl %d)\n",
- obj,
- obj->base.write_domain,
- !list_empty(&obj->gpu_write_list));
- err++;
+ for_each_ring(ring, dev_priv, i) {
+ if (list_empty(&ring->request_list)) {
+ if (!list_empty(&ring->active_list)) {
+ DRM_ERROR("%s: active list not empty, but no requests\n", ring->name);
+ err++;
+ }
+ continue;
}
- }
-
- list_for_each_entry(obj, &dev_priv->mm.flushing_list, list) {
- if (obj->base.dev != dev ||
- !atomic_read(&obj->base.refcount.refcount)) {
- DRM_ERROR("freed flushing %p\n", obj);
- err++;
- break;
- } else if (!obj->active ||
- (obj->base.write_domain & I915_GEM_GPU_DOMAINS) == 0 ||
- list_empty(&obj->gpu_write_list)) {
- DRM_ERROR("invalid flushing %p (a %d w %x gwl %d)\n",
- obj,
- obj->active,
- obj->base.write_domain,
- !list_empty(&obj->gpu_write_list));
- err++;
- }
- }
-
- list_for_each_entry(obj, &dev_priv->mm.gpu_write_list, gpu_write_list) {
- if (obj->base.dev != dev ||
- !atomic_read(&obj->base.refcount.refcount)) {
- DRM_ERROR("freed gpu write %p\n", obj);
- err++;
- break;
- } else if (!obj->active ||
- (obj->base.write_domain & I915_GEM_GPU_DOMAINS) == 0) {
- DRM_ERROR("invalid gpu write %p (a %d w %x)\n",
- obj,
- obj->active,
- obj->base.write_domain);
- err++;
- }
- }
- list_for_each_entry(obj, &i915_gtt_vm->inactive_list, list) {
- if (obj->base.dev != dev ||
- !atomic_read(&obj->base.refcount.refcount)) {
- DRM_ERROR("freed inactive %p\n", obj);
- err++;
- break;
- } else if (obj->pin_count || obj->active ||
- (obj->base.write_domain & I915_GEM_GPU_DOMAINS)) {
- DRM_ERROR("invalid inactive %p (p %d a %d w %x)\n",
- obj,
- obj->pin_count, obj->active,
- obj->base.write_domain);
- err++;
+ list_for_each_entry(obj, &ring->active_list, ring_list[ring->id]) {
+ if (obj->base.dev != dev ||
+ !atomic_read(&obj->base.refcount.refcount)) {
+ DRM_ERROR("%s: freed active obj %p\n",
+ ring->name, obj);
+ err++;
+ break;
+ } else if (!obj->active ||
+ obj->last_read_req[ring->id] == NULL) {
+ DRM_ERROR("%s: invalid active obj %p\n",
+ ring->name, obj);
+ err++;
+ } else if (obj->base.write_domain) {
+ DRM_ERROR("%s: invalid write obj %p (w %x)\n",
+ ring->name,
+ obj, obj->base.write_domain);
+ err++;
+ } else if (list_empty(&obj->last_read_req[ring->id]->list)) {
+ DRM_ERROR("%s: invalid request for obj %p\n",
+ ring->name, obj);
+ err++;
+ }
}
}
diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c
index a982849a5edd..fa5d53f1240f 100644
--- a/drivers/gpu/drm/i915/i915_gpu_error.c
+++ b/drivers/gpu/drm/i915/i915_gpu_error.c
@@ -192,15 +192,20 @@ static void print_error_buffers(struct drm_i915_error_state_buf *m,
struct drm_i915_error_buffer *err,
int count)
{
+ int i;
+
err_printf(m, " %s [%d]:\n", name, count);
while (count--) {
- err_printf(m, " %08x %8u %02x %02x %x %x",
+ err_printf(m, " %08x %8u %02x %02x [ ",
err->gtt_offset,
err->size,
err->read_domains,
- err->write_domain,
- err->rseqno, err->wseqno);
+ err->write_domain);
+ for (i = 0; i < I915_NUM_RINGS; i++)
+ err_printf(m, "%02x ", err->rseqno[i]);
+
+ err_printf(m, "] %02x", err->wseqno);
err_puts(m, pin_flag(err->pinned));
err_puts(m, tiling_flag(err->tiling));
err_puts(m, dirty_flag(err->dirty));
@@ -667,10 +672,12 @@ static void capture_bo(struct drm_i915_error_buffer *err,
struct i915_vma *vma)
{
struct drm_i915_gem_object *obj = vma->obj;
+ int i;
err->size = obj->base.size;
err->name = obj->base.name;
- err->rseqno = i915_gem_request_get_seqno(obj->last_read_req);
+ for (i = 0; i < I915_NUM_RINGS; i++)
+ err->rseqno[i] = i915_gem_request_get_seqno(obj->last_read_req[i]);
err->wseqno = i915_gem_request_get_seqno(obj->last_write_req);
err->gtt_offset = vma->node.start;
err->read_domains = obj->base.read_domains;
@@ -683,8 +690,8 @@ static void capture_bo(struct drm_i915_error_buffer *err,
err->dirty = obj->dirty;
err->purgeable = obj->madv != I915_MADV_WILLNEED;
err->userptr = obj->userptr.mm != NULL;
- err->ring = obj->last_read_req ?
- i915_gem_request_get_ring(obj->last_read_req)->id : -1;
+ err->ring = obj->last_write_req ?
+ i915_gem_request_get_ring(obj->last_write_req)->id : -1;
err->cache_level = obj->cache_level;
}
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 0efb19a9b9a5..1a3756e6bea4 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -9674,7 +9674,7 @@ static bool use_mmio_flip(struct intel_engine_cs *ring,
else if (i915.enable_execlists)
return true;
else
- return ring != i915_gem_request_get_ring(obj->last_read_req);
+ return ring != i915_gem_request_get_ring(obj->last_write_req);
}
Why this?
static void skl_do_mmio_flip(struct intel_crtc *intel_crtc)
@@ -9977,7 +9977,7 @@ static int intel_crtc_page_flip(struct drm_crtc *crtc,
} else if (IS_IVYBRIDGE(dev) || IS_HASWELL(dev)) {
ring = &dev_priv->ring[BCS];
} else if (INTEL_INFO(dev)->gen >= 7) {
- ring = i915_gem_request_get_ring(obj->last_read_req);
+ ring = i915_gem_request_get_ring(obj->last_write_req);
if (ring == NULL || ring->id != RCS)
ring = &dev_priv->ring[BCS];
} else {
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 1d08d8f9149d..a4a25c932b0b 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -129,6 +129,7 @@ struct intel_engine_cs {
VCS2
} id;
#define I915_NUM_RINGS 5
+#define I915_MAX_RING_BIT 3
#define LAST_USER_RING (VECS + 1)
u32 mmio_base;
struct drm_device *dev;
Regards,
Tvrtko
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