On 10/13/2021 10:51, Matthew Brost wrote:
On Tue, Oct 12, 2021 at 03:08:05PM -0700, John Harrison wrote:
On 10/4/2021 15:06, Matthew Brost wrote:
If an object in the excl or shared slot is a composite fence from a
parallel submit and the current request in the conflict tracking is from
the same parallel context there is no need to enforce ordering as the
ordering already implicit. Make the request conflict tracking understand
ordering already -> ordering is already
this by comparing the parents parallel fence values and skipping the
parents -> parent's
conflict insertion if the values match.
Presumably, this is to cope with the fact that the parallel submit fences do
not look like regular submission fences. And hence the existing code that
says 'new fence belongs to same context as old fence, so safe to ignore'
does not work with parallel submission. However, this change does not appear
to be adding parallel submit support to an existing 'same context' check. It
seems to be a brand new check that does not exist for single submission.
What makes parallel submit different? If we aren't skipping same context
fences for single submits, why do we need it for parallel? Conversely, if we
need it for parallel then why don't we need it for single?
And if the single submission version is simply somewhere else in the code,
why do the parallel version here instead of at the same place?
John.
Signed-off-by: Matthew Brost <matthew.brost@xxxxxxxxx>
---
drivers/gpu/drm/i915/i915_request.c | 43 +++++++++++++++++++----------
1 file changed, 29 insertions(+), 14 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
index e9bfa32f9270..cf89624020ad 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -1325,6 +1325,25 @@ i915_request_await_external(struct i915_request *rq, struct dma_fence *fence)
return err;
}
+static inline bool is_parallel_rq(struct i915_request *rq)
+{
+ return intel_context_is_parallel(rq->context);
+}
+
+static inline struct intel_context *request_to_parent(struct i915_request *rq)
+{
+ return intel_context_to_parent(rq->context);
+}
+
+static bool is_same_parallel_context(struct i915_request *to,
+ struct i915_request *from)
+{
+ if (is_parallel_rq(to))
Should this not say '&& is_parallel_rq(from)'?
Missed this one. That isn't necessary as if from is not a parallel
submit the following compare of parents will always return false. I
could add if you insist as either way works.
Matt
It was more a question of whether req_to_parent() works fine
irrespective of whether the rq is a parent, child or single?
John.
+ return request_to_parent(to) == request_to_parent(from);
+
+ return false;
+}
+
int
i915_request_await_execution(struct i915_request *rq,
struct dma_fence *fence)
@@ -1356,11 +1375,14 @@ i915_request_await_execution(struct i915_request *rq,
* want to run our callback in all cases.
*/
- if (dma_fence_is_i915(fence))
+ if (dma_fence_is_i915(fence)) {
+ if (is_same_parallel_context(rq, to_request(fence)))
+ continue;
ret = __i915_request_await_execution(rq,
to_request(fence));
- else
+ } else {
ret = i915_request_await_external(rq, fence);
+ }
if (ret < 0)
return ret;
} while (--nchild);
@@ -1461,10 +1483,13 @@ i915_request_await_dma_fence(struct i915_request *rq, struct dma_fence *fence)
fence))
continue;
- if (dma_fence_is_i915(fence))
+ if (dma_fence_is_i915(fence)) {
+ if (is_same_parallel_context(rq, to_request(fence)))
+ continue;
ret = i915_request_await_request(rq, to_request(fence));
- else
+ } else {
ret = i915_request_await_external(rq, fence);
+ }
if (ret < 0)
return ret;
@@ -1539,16 +1564,6 @@ i915_request_await_object(struct i915_request *to,
return ret;
}
-static inline bool is_parallel_rq(struct i915_request *rq)
-{
- return intel_context_is_parallel(rq->context);
-}
-
-static inline struct intel_context *request_to_parent(struct i915_request *rq)
-{
- return intel_context_to_parent(rq->context);
-}
-
static struct i915_request *
__i915_request_ensure_parallel_ordering(struct i915_request *rq,
struct intel_timeline *timeline)
