[Intel-gfx] [PATCH 2/8] drm/i915: Stop retiring along engine
Mika Kuoppala
mika.kuoppala at linux.intel.com
Fri Jun 14 14:23:15 UTC 2019
Chris Wilson <chris at chris-wilson.co.uk> writes:
> We no longer track the execution order along the engine and so no longer
> need to enforce ordering of retire along the engine.
>
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> ---
> drivers/gpu/drm/i915/i915_request.c | 128 +++++++++++-----------------
> 1 file changed, 52 insertions(+), 76 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
> index 9eff9de7fa10..9c58ae6e4afb 100644
> --- a/drivers/gpu/drm/i915/i915_request.c
> +++ b/drivers/gpu/drm/i915/i915_request.c
> @@ -183,72 +183,23 @@ static void free_capture_list(struct i915_request *request)
> }
> }
>
> -static void __retire_engine_request(struct intel_engine_cs *engine,
> - struct i915_request *rq)
> -{
> - GEM_TRACE("%s(%s) fence %llx:%lld, current %d\n",
> - __func__, engine->name,
> - rq->fence.context, rq->fence.seqno,
> - hwsp_seqno(rq));
> -
> - GEM_BUG_ON(!i915_request_completed(rq));
> -
> - local_irq_disable();
> -
> - spin_lock(&engine->timeline.lock);
> - GEM_BUG_ON(!list_is_first(&rq->link, &engine->timeline.requests));
> - list_del_init(&rq->link);
> - spin_unlock(&engine->timeline.lock);
> -
> - spin_lock(&rq->lock);
> - i915_request_mark_complete(rq);
> - if (!i915_request_signaled(rq))
> - dma_fence_signal_locked(&rq->fence);
> - if (test_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT, &rq->fence.flags))
> - i915_request_cancel_breadcrumb(rq);
> - if (rq->waitboost) {
> - GEM_BUG_ON(!atomic_read(&rq->i915->gt_pm.rps.num_waiters));
> - atomic_dec(&rq->i915->gt_pm.rps.num_waiters);
> - }
> - spin_unlock(&rq->lock);
> -
> - local_irq_enable();
> -}
> -
> -static void __retire_engine_upto(struct intel_engine_cs *engine,
> - struct i915_request *rq)
> -{
> - struct i915_request *tmp;
> -
> - if (list_empty(&rq->link))
> - return;
> -
> - do {
> - tmp = list_first_entry(&engine->timeline.requests,
> - typeof(*tmp), link);
> -
> - GEM_BUG_ON(tmp->engine != engine);
> - __retire_engine_request(engine, tmp);
> - } while (tmp != rq);
> -}
> -
> -static void i915_request_retire(struct i915_request *request)
> +static bool i915_request_retire(struct i915_request *rq)
> {
> struct i915_active_request *active, *next;
>
> - GEM_TRACE("%s fence %llx:%lld, current %d\n",
> - request->engine->name,
> - request->fence.context, request->fence.seqno,
> - hwsp_seqno(request));
> + lockdep_assert_held(&rq->i915->drm.struct_mutex);
> + if (!i915_request_completed(rq))
> + return false;
>
> - lockdep_assert_held(&request->i915->drm.struct_mutex);
> - GEM_BUG_ON(!i915_sw_fence_signaled(&request->submit));
> - GEM_BUG_ON(!i915_request_completed(request));
> + GEM_TRACE("%s fence %llx:%lld, current %d\n",
> + rq->engine->name,
> + rq->fence.context, rq->fence.seqno,
> + hwsp_seqno(rq));
>
> - trace_i915_request_retire(request);
> + GEM_BUG_ON(!i915_sw_fence_signaled(&rq->submit));
> + trace_i915_request_retire(rq);
>
> - advance_ring(request);
> - free_capture_list(request);
> + advance_ring(rq);
>
> /*
> * Walk through the active list, calling retire on each. This allows
> @@ -260,7 +211,7 @@ static void i915_request_retire(struct i915_request *request)
> * pass along the auxiliary information (to avoid dereferencing
> * the node after the callback).
> */
> - list_for_each_entry_safe(active, next, &request->active_list, link) {
> + list_for_each_entry_safe(active, next, &rq->active_list, link) {
> /*
> * In microbenchmarks or focusing upon time inside the kernel,
> * we may spend an inordinate amount of time simply handling
> @@ -276,18 +227,39 @@ static void i915_request_retire(struct i915_request *request)
> INIT_LIST_HEAD(&active->link);
> RCU_INIT_POINTER(active->request, NULL);
>
> - active->retire(active, request);
> + active->retire(active, rq);
> + }
> +
> + local_irq_disable();
> +
> + spin_lock(&rq->engine->timeline.lock);
> + list_del(&rq->link);
> + spin_unlock(&rq->engine->timeline.lock);
> +
> + spin_lock(&rq->lock);
> + i915_request_mark_complete(rq);
> + if (!i915_request_signaled(rq))
> + dma_fence_signal_locked(&rq->fence);
> + if (test_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT, &rq->fence.flags))
> + i915_request_cancel_breadcrumb(rq);
> + if (rq->waitboost) {
> + GEM_BUG_ON(!atomic_read(&rq->i915->gt_pm.rps.num_waiters));
> + atomic_dec(&rq->i915->gt_pm.rps.num_waiters);
> }
> + spin_unlock(&rq->lock);
> +
> + local_irq_enable();
>
> - i915_request_remove_from_client(request);
> + intel_context_exit(rq->hw_context);
> + intel_context_unpin(rq->hw_context);
>
> - __retire_engine_upto(request->engine, request);
> + i915_request_remove_from_client(rq);
>
> - intel_context_exit(request->hw_context);
> - intel_context_unpin(request->hw_context);
> + free_capture_list(rq);
> + i915_sched_node_fini(&rq->sched);
> + i915_request_put(rq);
>
> - i915_sched_node_fini(&request->sched);
> - i915_request_put(request);
> + return true;
> }
>
> void i915_request_retire_upto(struct i915_request *rq)
> @@ -309,9 +281,7 @@ void i915_request_retire_upto(struct i915_request *rq)
> do {
> tmp = list_first_entry(&ring->request_list,
> typeof(*tmp), ring_link);
> -
> - i915_request_retire(tmp);
> - } while (tmp != rq);
> + } while (i915_request_retire(tmp) && tmp != rq);
The semantics does change a little for this function. But
looking at the callsites it doesn't matter.
> }
>
> static void irq_execute_cb(struct irq_work *wrk)
> @@ -600,12 +570,9 @@ static void ring_retire_requests(struct intel_ring *ring)
> {
> struct i915_request *rq, *rn;
>
> - list_for_each_entry_safe(rq, rn, &ring->request_list, ring_link) {
> - if (!i915_request_completed(rq))
> + list_for_each_entry_safe(rq, rn, &ring->request_list, ring_link)
> + if (!i915_request_retire(rq))
> break;
> -
> - i915_request_retire(rq);
> - }
> }
>
> static noinline struct i915_request *
> @@ -620,6 +587,15 @@ request_alloc_slow(struct intel_context *ce, gfp_t gfp)
> if (!gfpflags_allow_blocking(gfp))
> goto out;
>
> + /* Move our oldest request to the slab-cache (if not in use!) */
> + rq = list_first_entry(&ring->request_list, typeof(*rq), ring_link);
> + i915_request_retire(rq);
Ok this is just for kick.
> +
> + rq = kmem_cache_alloc(global.slab_requests,
> + gfp | __GFP_RETRY_MAYFAIL | __GFP_NOWARN);
Only one callsite for this so you go cleaner by using gfp only if
you so desire.
Reviewed-by: Mika Kuoppala <mika.kuoppala at linux.intel.com>
> + if (rq)
> + return rq;
> +
> /* Ratelimit ourselves to prevent oom from malicious clients */
> rq = list_last_entry(&ring->request_list, typeof(*rq), ring_link);
> cond_synchronize_rcu(rq->rcustate);
> --
> 2.20.1
>
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