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

[Matthew Brost <matthew.brost@intel.com>]

On Wed, Jan 12, 2022 at 06:09:06PM +0100, Piotr Piórkowski wrote:
> Tvrtko Ursulin <tvrtko.ursulin@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.
> 

Agree. Didn't know if I could talk about SR-IOV publicly but clearly
can so add an explaination in the next rev.

> 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

Agree. I'll move these to functions in next rev.

Matt

> 
> - Piotr
> > > Signed-off-by: Matthew Brost <matthew.brost@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);
> > > 
> 
> --