[PATCH 2/4] drm/i915: Retire requests along rings
Chris Wilson
chris at chris-wilson.co.uk
Fri Apr 20 11:35:29 UTC 2018
In the next patch, rings are the central timeline as requests may jump
between engines. Therefore in the future as we retire in order along the
engine timeline, we may retire out-of-order within a ring (as the ring now
occurs along multiple engines), leading to much hilarity in miscomputing
the position of ring->head.
As an added bonus, retiring along the ring reduces the penalty of having
one execlists client do cleanup for another (old legacy submission
shares a ring between all clients). The downside is that slow and
irregular (off the critical path) process of cleaning up stale requests
after userspace becomes a modicum less efficient.
In the long run, it will become apparent that the ordered
ring->request_list matches the ring->timeline, a fun challenge for the
future will be unifying the two lists to avoid duplication!
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
---
drivers/gpu/drm/i915/i915_drv.h | 3 +-
drivers/gpu/drm/i915/i915_gem.c | 1 +
drivers/gpu/drm/i915/i915_request.c | 43 ++++++++-----------
drivers/gpu/drm/i915/intel_ringbuffer.c | 5 +++
drivers/gpu/drm/i915/intel_ringbuffer.h | 1 +
.../gpu/drm/i915/selftests/mock_gem_device.c | 1 +
6 files changed, 29 insertions(+), 25 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 028691108125..e177d2bda87d 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2055,8 +2055,9 @@ struct drm_i915_private {
void (*resume)(struct drm_i915_private *);
void (*cleanup_engine)(struct intel_engine_cs *engine);
- struct list_head timelines;
struct i915_gem_timeline global_timeline;
+ struct list_head timelines;
+ struct list_head rings;
u32 active_requests;
/**
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 795ca83aed7a..906e2395c245 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -5600,6 +5600,7 @@ int i915_gem_init_early(struct drm_i915_private *dev_priv)
goto err_dependencies;
mutex_lock(&dev_priv->drm.struct_mutex);
+ INIT_LIST_HEAD(&dev_priv->gt.rings);
INIT_LIST_HEAD(&dev_priv->gt.timelines);
err = i915_gem_timeline_init__global(dev_priv);
mutex_unlock(&dev_priv->drm.struct_mutex);
diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
index 1437538d5bfa..0bf949ec9f1a 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -292,6 +292,7 @@ void i915_gem_retire_noop(struct i915_gem_active *active,
static void advance_ring(struct i915_request *request)
{
+ struct intel_ring *ring = request->ring;
unsigned int tail;
/*
@@ -303,7 +304,9 @@ static void advance_ring(struct i915_request *request)
* Note this requires that we are always called in request
* completion order.
*/
- if (list_is_last(&request->ring_link, &request->ring->request_list)) {
+ GEM_BUG_ON(request != list_first_entry(&ring->request_list,
+ typeof(*request), ring_link));
+ if (list_is_last(&request->ring_link, &ring->request_list)) {
/*
* We may race here with execlists resubmitting this request
* as we retire it. The resubmission will move the ring->tail
@@ -318,7 +321,7 @@ static void advance_ring(struct i915_request *request)
}
list_del(&request->ring_link);
- request->ring->head = tail;
+ ring->head = tail;
}
static void free_capture_list(struct i915_request *request)
@@ -424,18 +427,18 @@ static void i915_request_retire(struct i915_request *request)
void i915_request_retire_upto(struct i915_request *rq)
{
- struct intel_engine_cs *engine = rq->engine;
+ struct intel_ring *ring = rq->ring;
struct i915_request *tmp;
lockdep_assert_held(&rq->i915->drm.struct_mutex);
GEM_BUG_ON(!i915_request_completed(rq));
- if (list_empty(&rq->link))
+ if (list_empty(&rq->ring_link))
return;
do {
- tmp = list_first_entry(&engine->timeline->requests,
- typeof(*tmp), link);
+ tmp = list_first_entry(&ring->request_list,
+ typeof(*tmp), ring_link);
i915_request_retire(tmp);
} while (tmp != rq);
@@ -644,9 +647,9 @@ i915_request_alloc(struct intel_engine_cs *engine, struct i915_gem_context *ctx)
if (ret)
goto err_unreserve;
- /* Move the oldest request to the slab-cache (if not in use!) */
- rq = list_first_entry_or_null(&engine->timeline->requests,
- typeof(*rq), link);
+ /* Move our oldest request to the slab-cache (if not in use!) */
+ rq = list_first_entry_or_null(&ring->request_list,
+ typeof(*rq), ring_link);
if (rq && i915_request_completed(rq))
i915_request_retire(rq);
@@ -1350,38 +1353,30 @@ long i915_request_wait(struct i915_request *rq,
return timeout;
}
-static void engine_retire_requests(struct intel_engine_cs *engine)
+static void ring_retire_requests(struct intel_ring *ring)
{
struct i915_request *request, *next;
- u32 seqno = intel_engine_get_seqno(engine);
- LIST_HEAD(retire);
- spin_lock_irq(&engine->timeline->lock);
list_for_each_entry_safe(request, next,
- &engine->timeline->requests, link) {
- if (!i915_seqno_passed(seqno, request->global_seqno))
+ &ring->request_list, ring_link) {
+ if (!i915_request_completed(request))
break;
- list_move_tail(&request->link, &retire);
- }
- spin_unlock_irq(&engine->timeline->lock);
-
- list_for_each_entry_safe(request, next, &retire, link)
i915_request_retire(request);
+ }
}
void i915_retire_requests(struct drm_i915_private *i915)
{
- struct intel_engine_cs *engine;
- enum intel_engine_id id;
+ struct intel_ring *ring, *next;
lockdep_assert_held(&i915->drm.struct_mutex);
if (!i915->gt.active_requests)
return;
- for_each_engine(engine, i915, id)
- engine_retire_requests(engine);
+ list_for_each_entry_safe(ring, next, &i915->gt.rings, link)
+ ring_retire_requests(ring);
}
#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index c68ac605b8a9..792a2ca95872 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -1124,6 +1124,7 @@ intel_engine_create_ring(struct intel_engine_cs *engine, int size)
GEM_BUG_ON(!is_power_of_2(size));
GEM_BUG_ON(RING_CTL_SIZE(size) & ~RING_NR_PAGES);
+ lockdep_assert_held(&engine->i915->drm.struct_mutex);
ring = kzalloc(sizeof(*ring), GFP_KERNEL);
if (!ring)
@@ -1149,6 +1150,8 @@ intel_engine_create_ring(struct intel_engine_cs *engine, int size)
}
ring->vma = vma;
+ list_add(&ring->link, &engine->i915->gt.rings);
+
return ring;
}
@@ -1160,6 +1163,8 @@ intel_ring_free(struct intel_ring *ring)
i915_vma_close(ring->vma);
__i915_gem_object_release_unless_active(obj);
+ list_del(&ring->link);
+
kfree(ring);
}
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index c5e27905b0e1..d816f8dea245 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -129,6 +129,7 @@ struct intel_ring {
void *vaddr;
struct list_head request_list;
+ struct list_head link;
u32 head;
u32 tail;
diff --git a/drivers/gpu/drm/i915/selftests/mock_gem_device.c b/drivers/gpu/drm/i915/selftests/mock_gem_device.c
index e6d4b882599a..4215f48e4a1c 100644
--- a/drivers/gpu/drm/i915/selftests/mock_gem_device.c
+++ b/drivers/gpu/drm/i915/selftests/mock_gem_device.c
@@ -224,6 +224,7 @@ struct drm_i915_private *mock_gem_device(void)
goto err_dependencies;
mutex_lock(&i915->drm.struct_mutex);
+ INIT_LIST_HEAD(&i915->gt.rings);
INIT_LIST_HEAD(&i915->gt.timelines);
err = i915_gem_timeline_init__global(i915);
if (err) {
--
2.17.0
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