[PATCH 44/55] drm/i915: Track requests inside each intel_ring

Chris Wilson
2016-07-25T17:40:54Z

By tracking each request occupying space inside an individual
intel_ring, we can greatly simplify the logic of tracking available
space and not worry about other timelines. (Each ring is an ordered
timeline of committed requests.)

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
drivers/gpu/drm/i915/i915_gem_request.c | 2 ++
drivers/gpu/drm/i915/i915_gem_request.h | 3 +++
drivers/gpu/drm/i915/intel_ringbuffer.c | 15 ++++-----------
drivers/gpu/drm/i915/intel_ringbuffer.h | 2 ++
4 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_request.c b/drivers/gpu/drm/i915/i915_gem_request.c
index 0216d6c093da..f1c37b7891cb 100644
--- a/drivers/gpu/drm/i915/i915_gem_request.c
+++ b/drivers/gpu/drm/i915/i915_gem_request.c
@@ -174,6 +174,7 @@ static void i915_gem_request_retire(struct drm_i915_gem_request *request)
* Note this requires that we are always called in request
* completion order.
*/
+ list_del(&request->ring_link);
request->ring->last_retired_head = request->postfix;

/* Walk through the active list, calling retire on each. This allows
@@ -472,6 +473,7 @@ void __i915_add_request(struct drm_i915_gem_request *request,
request->previous_seqno = engine->last_submitted_seqno;
smp_store_mb(engine->last_submitted_seqno, request->fence.seqno);
list_add_tail(&request->link, &engine->request_list);
+ list_add_tail(&request->ring_link, &ring->request_list);

/* Record the position of the start of the request so that
* should we detect the updated seqno part-way through the
diff --git a/drivers/gpu/drm/i915/i915_gem_request.h b/drivers/gpu/drm/i915/i915_gem_request.h
index f0b91207aaa4..b1ee37896feb 100644
--- a/drivers/gpu/drm/i915/i915_gem_request.h
+++ b/drivers/gpu/drm/i915/i915_gem_request.h
@@ -109,6 +109,9 @@ struct drm_i915_gem_request {
/** engine->request_list entry for this request */
struct list_head link;

+ /** ring->request_list entry for this request */
+ struct list_head ring_link;
+
struct drm_i915_file_private *file_priv;
/** file_priv list entry for this request */
struct list_head client_list;
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 5e0ba9416bd9..af76869c8db2 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -2059,6 +2059,8 @@ intel_engine_create_ring(struct intel_engine_cs *engine, int size)
ring->engine = engine;
list_add(&ring->link, &engine->buffers);

+ INIT_LIST_HEAD(&ring->request_list);
+
ring->size = size;
/* Workaround an erratum on the i830 which causes a hang if
* the TAIL pointer points to within the last 2 cachelines
@@ -2281,7 +2283,6 @@ int intel_ring_alloc_request_extras(struct drm_i915_gem_request *request)
static int wait_for_space(struct drm_i915_gem_request *req, int bytes)
{
struct intel_ring *ring = req->ring;
- struct intel_engine_cs *engine = req->engine;
struct drm_i915_gem_request *target;

intel_ring_update_space(ring);
@@ -2299,17 +2300,9 @@ static int wait_for_space(struct drm_i915_gem_request *req, int bytes)
*/
GEM_BUG_ON(!req->reserved_space);

- list_for_each_entry(target, &engine->request_list, link) {
+ list_for_each_entry(target, &ring->request_list, ring_link) {
unsigned space;

- /*
- * The request queue is per-engine, so can contain requests
- * from multiple ringbuffers. Here, we must ignore any that
- * aren't from the ringbuffer we're considering.
- */
- if (target->ring != ring)
- continue;
-
/* Would completion of this request free enough space? */
space = __intel_ring_space(target->postfix, ring->tail,
ring->size);
@@ -2317,7 +2310,7 @@ static int wait_for_space(struct drm_i915_gem_request *req, int bytes)
break;
}

- if (WARN_ON(&target->link == &engine->request_list))
+ if (WARN_ON(&target->ring_link == &ring->request_list))
return -ENOSPC;

return i915_wait_request(target);
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 51c059d8c917..2681106948a5 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -90,6 +90,8 @@ struct intel_ring {
struct intel_engine_cs *engine;
struct list_head link;

+ struct list_head request_list;
+
u32 head;
u32 tail;
int space;
--
2.8.1