[Intel-gfx] [PATCH] drm/i915: Flip guc_id allocation partition

[Piotr Piórkowski]

Tvrtko Ursulin <tvrtko.ursulin at linux.intel.com> wrote on śro [2022-sty-12 08:54:19 +0000]:
> 
> On 11/01/2022 16:30, Matthew Brost wrote:
> > Move the multi-lrc guc_id from the lower allocation partition (0 to
> > number of multi-lrc guc_ids) to upper allocation partition (number of
> > single-lrc to max guc_ids).
> 
> Just a reminder that best practice for commit messages is to include the
> "why" as well.
> 
> Regards,
> 
> Tvrtko
> 

 In my opinion this patch is good step forward.
 Lazy allocation of the bitmap for MLRC and moving the MLRC pool to the 
 end will allow easier development contexts for SR-IOV.
 Introduction of two new helpers (new_mlrc_guc_id and new_slrc_guc_id) cleans up the code.

 I agree with Tvrtko's comment that you should expand your commit
 message.

One thing I personally don't like is this NUMBER_SINGLE_LRC_GUC_ID definition (same for MLRC)
In my opinion it should be inline function and this value 1/16 defined as constant

- Piotr
> > Signed-off-by: Matthew Brost <matthew.brost at intel.com>
> > ---
> >   .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 57 ++++++++++++++-----
> >   1 file changed, 42 insertions(+), 15 deletions(-)
> > 
> > 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 9989d121127df..1bacc9621cea8 100644
> > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> > @@ -147,6 +147,8 @@ guc_create_parallel(struct intel_engine_cs **engines,
> >    */
> >   #define NUMBER_MULTI_LRC_GUC_ID(guc)	\
> >   	((guc)->submission_state.num_guc_ids / 16)
> > +#define NUMBER_SINGLE_LRC_GUC_ID(guc)	\
> > +	((guc)->submission_state.num_guc_ids - NUMBER_MULTI_LRC_GUC_ID(guc))
> >   /*
> >    * Below is a set of functions which control the GuC scheduling state which
> > @@ -1776,11 +1778,6 @@ int intel_guc_submission_init(struct intel_guc *guc)
> >   	INIT_WORK(&guc->submission_state.destroyed_worker,
> >   		  destroyed_worker_func);
> > -	guc->submission_state.guc_ids_bitmap =
> > -		bitmap_zalloc(NUMBER_MULTI_LRC_GUC_ID(guc), GFP_KERNEL);
> > -	if (!guc->submission_state.guc_ids_bitmap)
> > -		return -ENOMEM;
> > -
> >   	spin_lock_init(&guc->timestamp.lock);
> >   	INIT_DELAYED_WORK(&guc->timestamp.work, guc_timestamp_ping);
> >   	guc->timestamp.ping_delay = (POLL_TIME_CLKS / gt->clock_frequency + 1) * HZ;
> > @@ -1796,7 +1793,8 @@ void intel_guc_submission_fini(struct intel_guc *guc)
> >   	guc_flush_destroyed_contexts(guc);
> >   	guc_lrc_desc_pool_destroy(guc);
> >   	i915_sched_engine_put(guc->sched_engine);
> > -	bitmap_free(guc->submission_state.guc_ids_bitmap);
> > +	if (guc->submission_state.guc_ids_bitmap)
> > +		bitmap_free(guc->submission_state.guc_ids_bitmap);
> >   }
> >   static inline void queue_request(struct i915_sched_engine *sched_engine,
> > @@ -1863,6 +1861,33 @@ static void guc_submit_request(struct i915_request *rq)
> >   	spin_unlock_irqrestore(&sched_engine->lock, flags);
> >   }
> > +static int new_mlrc_guc_id(struct intel_guc *guc, struct intel_context *ce)
> > +{
> > +	int ret;
> > +
> > +	GEM_BUG_ON(!intel_context_is_parent(ce));
> > +	GEM_BUG_ON(!guc->submission_state.guc_ids_bitmap);
> > +
> > +	ret =  bitmap_find_free_region(guc->submission_state.guc_ids_bitmap,
> > +				       NUMBER_MULTI_LRC_GUC_ID(guc),
> > +				       order_base_2(ce->parallel.number_children
> > +						    + 1));
> > +	if (likely(!(ret < 0)))
> > +		ret += NUMBER_SINGLE_LRC_GUC_ID(guc);
> > +
> > +	return ret;
> > +}
> > +
> > +static int new_slrc_guc_id(struct intel_guc *guc, struct intel_context *ce)
> > +{
> > +	GEM_BUG_ON(intel_context_is_parent(ce));
> > +
> > +	return ida_simple_get(&guc->submission_state.guc_ids,
> > +			      0, NUMBER_SINGLE_LRC_GUC_ID(guc),
> > +			      GFP_KERNEL | __GFP_RETRY_MAYFAIL |
> > +			      __GFP_NOWARN);
> > +}
> > +
> >   static int new_guc_id(struct intel_guc *guc, struct intel_context *ce)
> >   {
> >   	int ret;
> > @@ -1870,16 +1895,10 @@ static int new_guc_id(struct intel_guc *guc, struct intel_context *ce)
> >   	GEM_BUG_ON(intel_context_is_child(ce));
> >   	if (intel_context_is_parent(ce))
> > -		ret = bitmap_find_free_region(guc->submission_state.guc_ids_bitmap,
> > -					      NUMBER_MULTI_LRC_GUC_ID(guc),
> > -					      order_base_2(ce->parallel.number_children
> > -							   + 1));
> > +		ret = new_mlrc_guc_id(guc, ce);
> >   	else
> > -		ret = ida_simple_get(&guc->submission_state.guc_ids,
> > -				     NUMBER_MULTI_LRC_GUC_ID(guc),
> > -				     guc->submission_state.num_guc_ids,
> > -				     GFP_KERNEL | __GFP_RETRY_MAYFAIL |
> > -				     __GFP_NOWARN);
> > +		ret = new_slrc_guc_id(guc, ce);
> > +
> >   	if (unlikely(ret < 0))
> >   		return ret;
> > @@ -1989,6 +2008,14 @@ static int pin_guc_id(struct intel_guc *guc, struct intel_context *ce)
> >   	GEM_BUG_ON(atomic_read(&ce->guc_id.ref));
> > +	if (unlikely(intel_context_is_parent(ce) &&
> > +		     !guc->submission_state.guc_ids_bitmap)) {
> > +		guc->submission_state.guc_ids_bitmap =
> > +			bitmap_zalloc(NUMBER_MULTI_LRC_GUC_ID(guc), GFP_KERNEL);
> > +		if (!guc->submission_state.guc_ids_bitmap)
> > +			return -ENOMEM;
> > +	}
> > +
> >   try_again:
> >   	spin_lock_irqsave(&guc->submission_state.lock, flags);
> > 

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