Re: [PATCH] drm/i915/execlists: Tweak virtual unsubmission

[Ramalingam C <ramalingam.c@intel.com>]

On 2019-10-13 at 21:30:12 +0100, Chris Wilson wrote:
> Since commit e2144503bf3b ("drm/i915: Prevent bonded requests from
> overtaking each other on preemption") we have restricted requests to run
> on their chosen engine across preemption events. We can take this
> restriction into account to know that we will want to resubmit those
> requests onto the same physical engine, and so can shortcircuit the
> virtual engine selection process and keep the request on the same
> engine during unwind.
> 
> References: e2144503bf3b ("drm/i915: Prevent bonded requests from overtaking each other on preemption")
Chris,

Based on what i understood here, change looks good to me.

If it helps, please use
Reviewed-by: Ramlingam C <ramalingam.c@intel.com>

> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> ---
>  drivers/gpu/drm/i915/gt/intel_lrc.c | 6 +++---
>  drivers/gpu/drm/i915/i915_request.c | 2 +-
>  2 files changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
> index e6bf633b48d5..03732e3f5ec7 100644
> --- a/drivers/gpu/drm/i915/gt/intel_lrc.c
> +++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
> @@ -895,7 +895,6 @@ __unwind_incomplete_requests(struct intel_engine_cs *engine)
>  	list_for_each_entry_safe_reverse(rq, rn,
>  					 &engine->active.requests,
>  					 sched.link) {
> -		struct intel_engine_cs *owner;
>  
>  		if (i915_request_completed(rq))
>  			continue; /* XXX */
> @@ -910,8 +909,7 @@ __unwind_incomplete_requests(struct intel_engine_cs *engine)
>  		 * engine so that it can be moved across onto another physical
>  		 * engine as load dictates.
>  		 */
> -		owner = rq->hw_context->engine;
> -		if (likely(owner == engine)) {
> +		if (likely(rq->execution_mask == engine->mask)) {
>  			GEM_BUG_ON(rq_prio(rq) == I915_PRIORITY_INVALID);
>  			if (rq_prio(rq) != prio) {
>  				prio = rq_prio(rq);
> @@ -922,6 +920,8 @@ __unwind_incomplete_requests(struct intel_engine_cs *engine)
>  			list_move(&rq->sched.link, pl);
>  			active = rq;
>  		} else {
> +			struct intel_engine_cs *owner = rq->hw_context->engine;
> +
>  			/*
>  			 * Decouple the virtual breadcrumb before moving it
>  			 * back to the virtual engine -- we don't want the
> diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
> index 437f9fc6282e..b8a54572a4f8 100644
> --- a/drivers/gpu/drm/i915/i915_request.c
> +++ b/drivers/gpu/drm/i915/i915_request.c
> @@ -649,6 +649,7 @@ __i915_request_create(struct intel_context *ce, gfp_t gfp)
>  	rq->gem_context = ce->gem_context;
>  	rq->engine = ce->engine;
>  	rq->ring = ce->ring;
> +	rq->execution_mask = ce->engine->mask;
>  
>  	rcu_assign_pointer(rq->timeline, tl);
>  	rq->hwsp_seqno = tl->hwsp_seqno;
> @@ -671,7 +672,6 @@ __i915_request_create(struct intel_context *ce, gfp_t gfp)
>  	rq->batch = NULL;
>  	rq->capture_list = NULL;
>  	rq->flags = 0;
> -	rq->execution_mask = ALL_ENGINES;
>  
>  	INIT_LIST_HEAD(&rq->execute_cb);
>  
> -- 
> 2.23.0
> 
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