linux-kernel - Re: [PATCH v2 2/2] block/blk-mq: Don't complete locally if capacities are different

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Date: Sat, 24 Feb 2024 23:06:24 +0000
From: Qais Yousef <qyousef@...alina.io>
To: Bart Van Assche <bvanassche@....org>
Cc: Jens Axboe <axboe@...nel.dk>, Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Dietmar Eggemann <dietmar.eggemann@....com>,
	linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
	Sudeep Holla <sudeep.holla@....com>, Wei Wang <wvw@...gle.com>,
	Jaegeuk Kim <jaegeuk@...nel.org>,
	Christoph Hellwig <hch@...radead.org>
Subject: Re: [PATCH v2 2/2] block/blk-mq: Don't complete locally if
 capacities are different

On 02/23/24 08:09, Bart Van Assche wrote:
> On 2/23/24 07:57, Qais Yousef wrote:
> > diff --git a/block/blk-mq.c b/block/blk-mq.c
> > index 2dc01551e27c..ea69047e12f7 100644
> > --- a/block/blk-mq.c
> > +++ b/block/blk-mq.c
> > @@ -1167,10 +1167,11 @@ static inline bool blk_mq_complete_need_ipi(struct request *rq)
> >   	if (force_irqthreads())
> >   		return false;
> > -	/* same CPU or cache domain?  Complete locally */
> > +	/* same CPU or cache domain and capacity?  Complete locally */
> >   	if (cpu == rq->mq_ctx->cpu ||
> >   	    (!test_bit(QUEUE_FLAG_SAME_FORCE, &rq->q->queue_flags) &&
> > -	     cpus_share_cache(cpu, rq->mq_ctx->cpu)))
> > +	     cpus_share_cache(cpu, rq->mq_ctx->cpu) &&
> > +	     cpus_equal_capacity(cpu, rq->mq_ctx->cpu)))
> >   		return false;
> >   	/* don't try to IPI to an offline CPU */
> 
> I think it's worth mentioning that this change is intended for storage
> controllers that only support a single completion interrupt. Anyway:

Sorry I didn't realize it is only applied for this scenario.

> 
> Reviewed-by: Bart Van Assche <bvanassche@....org>

Thanks for the reviews!