On Fri, Jun 04, 2021 at 02:17:58PM -0500, Jason Ekstrand wrote:
> On Thu, Jun 3, 2021 at 4:09 PM Matthew Brost <matthew.brost@xxxxxxxxx> wrote:
> >
> > Rather passing around an intel_engine_cs in the scheduling code, pass
> > around a i915_sched_engine.
>
> 👍
>
> > Signed-off-by: Matthew Brost <matthew.brost@xxxxxxxxx>
> > ---
> > .../drm/i915/gt/intel_execlists_submission.c | 11 +++--
> > .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 2 +-
> > drivers/gpu/drm/i915/i915_scheduler.c | 46 +++++++++----------
> > drivers/gpu/drm/i915/i915_scheduler.h | 2 +-
> > 4 files changed, 32 insertions(+), 29 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> > index 3fac17103837..7240c153be35 100644
> > --- a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> > +++ b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> > @@ -382,7 +382,8 @@ __unwind_incomplete_requests(struct intel_engine_cs *engine)
> > GEM_BUG_ON(rq_prio(rq) == I915_PRIORITY_INVALID);
> > if (rq_prio(rq) != prio) {
> > prio = rq_prio(rq);
> > - pl = i915_sched_lookup_priolist(engine, prio);
> > + pl = i915_sched_lookup_priolist(engine->sched_engine,
> > + prio);
> > }
> > GEM_BUG_ON(i915_sched_engine_is_empty(engine->sched_engine));
> >
> > @@ -1096,7 +1097,8 @@ static void defer_active(struct intel_engine_cs *engine)
> > if (!rq)
> > return;
> >
> > - defer_request(rq, i915_sched_lookup_priolist(engine, rq_prio(rq)));
> > + defer_request(rq, i915_sched_lookup_priolist(engine->sched_engine,
> > + rq_prio(rq)));
> > }
> >
> > static bool
> > @@ -2083,7 +2085,7 @@ static void __execlists_unhold(struct i915_request *rq)
> >
> > i915_request_clear_hold(rq);
> > list_move_tail(&rq->sched.link,
> > - i915_sched_lookup_priolist(rq->engine,
> > + i915_sched_lookup_priolist(rq->engine->sched_engine,
> > rq_prio(rq)));
> > set_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
> >
> > @@ -2452,7 +2454,8 @@ static void queue_request(struct intel_engine_cs *engine,
> > {
> > GEM_BUG_ON(!list_empty(&rq->sched.link));
> > list_add_tail(&rq->sched.link,
> > - i915_sched_lookup_priolist(engine, rq_prio(rq)));
> > + i915_sched_lookup_priolist(engine->sched_engine,
> > + rq_prio(rq)));
> > set_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
> > }
> >
> > diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> > index 4c5bbec0775d..7ed21670ef14 100644
> > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> > @@ -529,7 +529,7 @@ static inline void queue_request(struct intel_engine_cs *engine,
> > {
> > GEM_BUG_ON(!list_empty(&rq->sched.link));
> > list_add_tail(&rq->sched.link,
> > - i915_sched_lookup_priolist(engine, prio));
> > + i915_sched_lookup_priolist(engine->sched_engine, prio));
> > set_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
> > }
> >
> > diff --git a/drivers/gpu/drm/i915/i915_scheduler.c b/drivers/gpu/drm/i915/i915_scheduler.c
> > index 035b88f2e4aa..3d36e4447b5d 100644
> > --- a/drivers/gpu/drm/i915/i915_scheduler.c
> > +++ b/drivers/gpu/drm/i915/i915_scheduler.c
> > @@ -61,14 +61,13 @@ static void assert_priolists(struct i915_sched_engine * const sched_engine)
> > }
> >
> > struct list_head *
> > -i915_sched_lookup_priolist(struct intel_engine_cs *engine, int prio)
> > +i915_sched_lookup_priolist(struct i915_sched_engine *sched_engine, int prio)
> > {
> > - struct i915_sched_engine * const sched_engine = engine->sched_engine;
> > struct i915_priolist *p;
> > struct rb_node **parent, *rb;
> > bool first = true;
> >
> > - lockdep_assert_held(&engine->sched_engine->lock);
> > + lockdep_assert_held(&sched_engine->lock);
> > assert_priolists(sched_engine);
> >
> > if (unlikely(sched_engine->no_priolist))
> > @@ -130,13 +129,13 @@ struct sched_cache {
> > struct list_head *priolist;
> > };
> >
> > -static struct intel_engine_cs *
> > -sched_lock_engine(const struct i915_sched_node *node,
> > - struct intel_engine_cs *locked,
> > +static struct i915_sched_engine *
> > +lock_sched_engine(struct i915_sched_node *node,
> > + struct i915_sched_engine *locked,
> > struct sched_cache *cache)
> > {
> > const struct i915_request *rq = node_to_request(node);
> > - struct intel_engine_cs *engine;
> > + struct i915_sched_engine *sched_engine;
> >
> > GEM_BUG_ON(!locked);
> >
> > @@ -146,14 +145,14 @@ sched_lock_engine(const struct i915_sched_node *node,
> > * engine lock. The simple ploy we use is to take the lock then
> > * check that the rq still belongs to the newly locked engine.
> > */
> > - while (locked != (engine = READ_ONCE(rq->engine))) {
> > - spin_unlock(&locked->sched_engine->lock);
> > + while (locked != (sched_engine = rq->engine->sched_engine)) {
>
> You lost the READ_ONCE here. Based on the comment above, that may
> matter. I guess it depends on what all barriers spin_lock() implies.
>
Ah, good catch. I think it should be:
READ_ONCE(rq->engine)->sched_engine
As the rq->engine is the unstable pointer.
Matt
> Assuming that's all good,
>
> Reviewed-by: Jason Ekstrand <jason@xxxxxxxxxxxxxx>
>
> > + spin_unlock(&locked->lock);
> > memset(cache, 0, sizeof(*cache));
> > - spin_lock(&engine->sched_engine->lock);
> > - locked = engine;
> > + spin_lock(&sched_engine->lock);
> > + locked = sched_engine;
> > }
> >
> > - GEM_BUG_ON(locked != engine);
> > + GEM_BUG_ON(locked != sched_engine);
> > return locked;
> > }
> >
> > @@ -161,7 +160,7 @@ static void __i915_schedule(struct i915_sched_node *node,
> > const struct i915_sched_attr *attr)
> > {
> > const int prio = max(attr->priority, node->attr.priority);
> > - struct intel_engine_cs *engine;
> > + struct i915_sched_engine *sched_engine;
> > struct i915_dependency *dep, *p;
> > struct i915_dependency stack;
> > struct sched_cache cache;
> > @@ -236,23 +235,24 @@ static void __i915_schedule(struct i915_sched_node *node,
> > }
> >
> > memset(&cache, 0, sizeof(cache));
> > - engine = node_to_request(node)->engine;
> > - spin_lock(&engine->sched_engine->lock);
> > + sched_engine = node_to_request(node)->engine->sched_engine;
> > + spin_lock(&sched_engine->lock);
> >
> > /* Fifo and depth-first replacement ensure our deps execute before us */
> > - engine = sched_lock_engine(node, engine, &cache);
> > + sched_engine = lock_sched_engine(node, sched_engine, &cache);
> > list_for_each_entry_safe_reverse(dep, p, &dfs, dfs_link) {
> > INIT_LIST_HEAD(&dep->dfs_link);
> >
> > node = dep->signaler;
> > - engine = sched_lock_engine(node, engine, &cache);
> > - lockdep_assert_held(&engine->sched_engine->lock);
> > + sched_engine = lock_sched_engine(node, sched_engine, &cache);
> > + lockdep_assert_held(&sched_engine->lock);
> >
> > /* Recheck after acquiring the engine->timeline.lock */
> > if (prio <= node->attr.priority || node_signaled(node))
> > continue;
> >
> > - GEM_BUG_ON(node_to_request(node)->engine != engine);
> > + GEM_BUG_ON(node_to_request(node)->engine->sched_engine !=
> > + sched_engine);
> >
> > WRITE_ONCE(node->attr.priority, prio);
> >
> > @@ -270,17 +270,17 @@ static void __i915_schedule(struct i915_sched_node *node,
> > if (i915_request_in_priority_queue(node_to_request(node))) {
> > if (!cache.priolist)
> > cache.priolist =
> > - i915_sched_lookup_priolist(engine,
> > + i915_sched_lookup_priolist(sched_engine,
> > prio);
> > list_move_tail(&node->link, cache.priolist);
> > }
> >
> > /* Defer (tasklet) submission until after all of our updates. */
> > - if (engine->sched_engine->kick_backend)
> > - engine->sched_engine->kick_backend(node_to_request(node), prio);
> > + if (sched_engine->kick_backend)
> > + sched_engine->kick_backend(node_to_request(node), prio);
> > }
> >
> > - spin_unlock(&engine->sched_engine->lock);
> > + spin_unlock(&sched_engine->lock);
> > }
> >
> > void i915_schedule(struct i915_request *rq, const struct i915_sched_attr *attr)
> > diff --git a/drivers/gpu/drm/i915/i915_scheduler.h b/drivers/gpu/drm/i915/i915_scheduler.h
> > index 713c38c99de9..0014745bda30 100644
> > --- a/drivers/gpu/drm/i915/i915_scheduler.h
> > +++ b/drivers/gpu/drm/i915/i915_scheduler.h
> > @@ -39,7 +39,7 @@ void i915_schedule(struct i915_request *request,
> > const struct i915_sched_attr *attr);
> >
> > struct list_head *
> > -i915_sched_lookup_priolist(struct intel_engine_cs *engine, int prio);
> > +i915_sched_lookup_priolist(struct i915_sched_engine *sched_engine, int prio);
> >
> > void __i915_priolist_free(struct i915_priolist *p);
> > static inline void i915_priolist_free(struct i915_priolist *p)
> > --
> > 2.28.0
> >
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
> > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
