Re: [PATCH 14/25] drm/i915/guc: Implement multi-lrc reset

From: John Harrison <john.c.harrison@intel.com>
To: Matthew Brost <matthew.brost@intel.com>,
	<intel-gfx@lists.freedesktop.org>,
	<dri-devel@lists.freedesktop.org>
Subject: Re: [PATCH 14/25] drm/i915/guc: Implement multi-lrc reset
Date: Wed, 13 Oct 2021 17:28:05 -0700	[thread overview]
Message-ID: <67b6991c-a789-e2af-6fdb-5941d0e89e75@intel.com> (raw)
In-Reply-To: <20211013204231.19287-15-matthew.brost@intel.com>

On 10/13/2021 13:42, Matthew Brost wrote:
> Update context and full GPU reset to work with multi-lrc. The idea is
> parent context tracks all the active requests inflight for itself and
> its children. The parent context owns the reset replaying / canceling
> requests as needed.
>
> v2:
>   (John Harrison)
>    - Simply loop in find active request
>    - Add comments to find ative request / reset loop
> v3:
>   (John Harrison)
>    - s/its'/its/g
>    - Fix comment when searching for active request
>    - Reorder if state in __guc_reset_context
>
> Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: John Harrison <John.C.Harrison@Intel.com>

> ---
>   drivers/gpu/drm/i915/gt/intel_context.c       | 15 +++-
>   .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 69 ++++++++++++++-----
>   2 files changed, 63 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/intel_context.c b/drivers/gpu/drm/i915/gt/intel_context.c
> index 79f321c6c008..6aab60584ee5 100644
> --- a/drivers/gpu/drm/i915/gt/intel_context.c
> +++ b/drivers/gpu/drm/i915/gt/intel_context.c
> @@ -529,20 +529,29 @@ struct i915_request *intel_context_create_request(struct intel_context *ce)
>   
>   struct i915_request *intel_context_find_active_request(struct intel_context *ce)
>   {
> +	struct intel_context *parent = intel_context_to_parent(ce);
>   	struct i915_request *rq, *active = NULL;
>   	unsigned long flags;
>   
>   	GEM_BUG_ON(!intel_engine_uses_guc(ce->engine));
>   
> -	spin_lock_irqsave(&ce->guc_state.lock, flags);
> -	list_for_each_entry_reverse(rq, &ce->guc_state.requests,
> +	/*
> +	 * We search the parent list to find an active request on the submitted
> +	 * context. The parent list contains the requests for all the contexts
> +	 * in the relationship so we have to do a compare of each request's
> +	 * context.
> +	 */
> +	spin_lock_irqsave(&parent->guc_state.lock, flags);
> +	list_for_each_entry_reverse(rq, &parent->guc_state.requests,
>   				    sched.link) {
> +		if (rq->context != ce)
> +			continue;
>   		if (i915_request_completed(rq))
>   			break;
>   
>   		active = rq;
>   	}
> -	spin_unlock_irqrestore(&ce->guc_state.lock, flags);
> +	spin_unlock_irqrestore(&parent->guc_state.lock, flags);
>   
>   	return active;
>   }
> 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 f690b7c2b295..bc052d206861 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> @@ -683,6 +683,11 @@ static inline int rq_prio(const struct i915_request *rq)
>   	return rq->sched.attr.priority;
>   }
>   
> +static inline bool is_multi_lrc(struct intel_context *ce)
> +{
> +	return intel_context_is_parallel(ce);
> +}
> +
>   static bool is_multi_lrc_rq(struct i915_request *rq)
>   {
>   	return intel_context_is_parallel(rq->context);
> @@ -1218,10 +1223,15 @@ __unwind_incomplete_requests(struct intel_context *ce)
>   
>   static void __guc_reset_context(struct intel_context *ce, bool stalled)
>   {
> +	bool local_stalled;
>   	struct i915_request *rq;
>   	unsigned long flags;
>   	u32 head;
> +	int i, number_children = ce->parallel.number_children;
>   	bool skip = false;
> +	struct intel_context *parent = ce;
> +
> +	GEM_BUG_ON(intel_context_is_child(ce));
>   
>   	intel_context_get(ce);
>   
> @@ -1247,25 +1257,38 @@ static void __guc_reset_context(struct intel_context *ce, bool stalled)
>   	if (unlikely(skip))
>   		goto out_put;
>   
> -	rq = intel_context_find_active_request(ce);
> -	if (!rq) {
> -		head = ce->ring->tail;
> -		stalled = false;
> -		goto out_replay;
> -	}
> +	/*
> +	 * For each context in the relationship find the hanging request
> +	 * resetting each context / request as needed
> +	 */
> +	for (i = 0; i < number_children + 1; ++i) {
> +		if (!intel_context_is_pinned(ce))
> +			goto next_context;
> +
> +		local_stalled = false;
> +		rq = intel_context_find_active_request(ce);
> +		if (!rq) {
> +			head = ce->ring->tail;
> +			goto out_replay;
> +		}
>   
> -	if (!i915_request_started(rq))
> -		stalled = false;
> +		if (i915_request_started(rq))
> +			local_stalled = true;
>   
> -	GEM_BUG_ON(i915_active_is_idle(&ce->active));
> -	head = intel_ring_wrap(ce->ring, rq->head);
> -	__i915_request_reset(rq, stalled);
> +		GEM_BUG_ON(i915_active_is_idle(&ce->active));
> +		head = intel_ring_wrap(ce->ring, rq->head);
>   
> +		__i915_request_reset(rq, local_stalled && stalled);
>   out_replay:
> -	guc_reset_state(ce, head, stalled);
> -	__unwind_incomplete_requests(ce);
> +		guc_reset_state(ce, head, local_stalled && stalled);
> +next_context:
> +		if (i != number_children)
> +			ce = list_next_entry(ce, parallel.child_link);
> +	}
> +
> +	__unwind_incomplete_requests(parent);
>   out_put:
> -	intel_context_put(ce);
> +	intel_context_put(parent);
>   }
>   
>   void intel_guc_submission_reset(struct intel_guc *guc, bool stalled)
> @@ -1286,7 +1309,8 @@ void intel_guc_submission_reset(struct intel_guc *guc, bool stalled)
>   
>   		xa_unlock(&guc->context_lookup);
>   
> -		if (intel_context_is_pinned(ce))
> +		if (intel_context_is_pinned(ce) &&
> +		    !intel_context_is_child(ce))
>   			__guc_reset_context(ce, stalled);
>   
>   		intel_context_put(ce);
> @@ -1378,7 +1402,8 @@ void intel_guc_submission_cancel_requests(struct intel_guc *guc)
>   
>   		xa_unlock(&guc->context_lookup);
>   
> -		if (intel_context_is_pinned(ce))
> +		if (intel_context_is_pinned(ce) &&
> +		    !intel_context_is_child(ce))
>   			guc_cancel_context_requests(ce);
>   
>   		intel_context_put(ce);
> @@ -2071,6 +2096,8 @@ static struct i915_sw_fence *guc_context_block(struct intel_context *ce)
>   	u16 guc_id;
>   	bool enabled;
>   
> +	GEM_BUG_ON(intel_context_is_child(ce));
> +
>   	spin_lock_irqsave(&ce->guc_state.lock, flags);
>   
>   	incr_context_blocked(ce);
> @@ -2125,6 +2152,7 @@ static void guc_context_unblock(struct intel_context *ce)
>   	bool enable;
>   
>   	GEM_BUG_ON(context_enabled(ce));
> +	GEM_BUG_ON(intel_context_is_child(ce));
>   
>   	spin_lock_irqsave(&ce->guc_state.lock, flags);
>   
> @@ -2151,11 +2179,14 @@ static void guc_context_unblock(struct intel_context *ce)
>   static void guc_context_cancel_request(struct intel_context *ce,
>   				       struct i915_request *rq)
>   {
> +	struct intel_context *block_context =
> +		request_to_scheduling_context(rq);
> +
>   	if (i915_sw_fence_signaled(&rq->submit)) {
>   		struct i915_sw_fence *fence;
>   
>   		intel_context_get(ce);
> -		fence = guc_context_block(ce);
> +		fence = guc_context_block(block_context);
>   		i915_sw_fence_wait(fence);
>   		if (!i915_request_completed(rq)) {
>   			__i915_request_skip(rq);
> @@ -2169,7 +2200,7 @@ static void guc_context_cancel_request(struct intel_context *ce,
>   		 */
>   		flush_work(&ce_to_guc(ce)->ct.requests.worker);
>   
> -		guc_context_unblock(ce);
> +		guc_context_unblock(block_context);
>   		intel_context_put(ce);
>   	}
>   }
> @@ -2195,6 +2226,8 @@ static void guc_context_ban(struct intel_context *ce, struct i915_request *rq)
>   	intel_wakeref_t wakeref;
>   	unsigned long flags;
>   
> +	GEM_BUG_ON(intel_context_is_child(ce));
> +
>   	guc_flush_submissions(guc);
>   
>   	spin_lock_irqsave(&ce->guc_state.lock, flags);