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From: Bart Van Assche <Bart.VanAssche@wdc.com>
To: "hch@infradead.org" <hch@infradead.org>,
	"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
	"snitzer@redhat.com" <snitzer@redhat.com>,
	"ming.lei@redhat.com" <ming.lei@redhat.com>,
	"axboe@kernel.dk" <axboe@kernel.dk>
Cc: "hch@lst.de" <hch@lst.de>,
	"martin.petersen@oracle.com" <martin.petersen@oracle.com>,
	"hare@suse.de" <hare@suse.de>,
	"linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
	"don.brace@microsemi.com" <don.brace@microsemi.com>,
	"james.bottomley@hansenpartnership.com"
	<james.bottomley@hansenpartnership.com>,
	"pbonzini@redhat.com" <pbonzini@redhat.com>,
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	"osandov@fb.com" <osandov@fb.com>,
	"loberman@redhat.com" <loberman@redhat.com>,
	"kashyap.desai@broadcom.com" <kashyap.desai@broadcom.com>,
	"peter.rivera@broadcom.com" <peter.rivera@broadcom.com>
Subject: Re: [PATCH V2 2/8] blk-mq: introduce BLK_MQ_F_GLOBAL_TAGS
Date: Thu, 8 Feb 2018 15:25:51 +0000	[thread overview]
Message-ID: <1518103548.6826.2.camel@wdc.com> (raw)
In-Reply-To: <20180205152035.15016-3-ming.lei@redhat.com>

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WARNING: multiple messages have this Message-ID (diff)
From: Bart Van Assche <Bart.VanAssche@wdc.com>
To: "hch@infradead.org" <hch@infradead.org>,
	"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
	"snitzer@redhat.com" <snitzer@redhat.com>,
	"ming.lei@redhat.com" <ming.lei@redhat.com>,
	"axboe@kernel.dk" <axboe@kernel.dk>
Cc: "hch@lst.de" <hch@lst.de>,
	"martin.petersen@oracle.com" <martin.petersen@oracle.com>,
	"hare@suse.de" <hare@suse.de>,
	"linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
	"don.brace@microsemi.com" <don.brace@microsemi.com>,
	"james.bottomley@hansenpartnership.com"
	<james.bottomley@hansenpartnership.com>,
	"pbonzini@redhat.com" <pbonzini@redhat.com>,
	"arun.easi@cavium.com" <arun.easi@cavium.com>,
	"osandov@fb.com" <osandov@fb.com>,
	"loberman@redhat.com" <loberman@redhat.com>,
	"kashyap.desai@broadcom.com" <kashyap.desai@broadcom.com>,
	"peter.rivera@broadcom.com" <peter.rivera@broadcom.com>
Subject: Re: [PATCH V2 2/8] blk-mq: introduce BLK_MQ_F_GLOBAL_TAGS
Date: Thu, 8 Feb 2018 15:25:51 +0000	[thread overview]
Message-ID: <1518103548.6826.2.camel@wdc.com> (raw)
In-Reply-To: <20180205152035.15016-3-ming.lei@redhat.com>

On Mon, 2018-02-05 at 23:20 +0800, Ming Lei wrote:
> diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
> index 55c0a745b427..385bbec73804 100644
> --- a/block/blk-mq-sched.c
> +++ b/block/blk-mq-sched.c
> @@ -81,6 +81,17 @@ static bool blk_mq_sched_restart_hctx(struct blk_mq_hw_ctx *hctx)
>  	} else
>  		clear_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state);
>  
> +	/* need to restart all hw queues for global tags */
> +	if (hctx->flags & BLK_MQ_F_GLOBAL_TAGS) {
> +		struct blk_mq_hw_ctx *hctx2;
> +		int i;
> +
> +		queue_for_each_hw_ctx(hctx->queue, hctx2, i)
> +			if (blk_mq_run_hw_queue(hctx2, true))
> +				return true;
> +		return false;
> +	}
> +
>  	return blk_mq_run_hw_queue(hctx, true);
>  }

It seems weird to me that no matter for which hardware queue a restart is
requested (the hctx argument) that the above loop starts with examining
the hardware queue with index 0. Will this cause fairness and/or cache
line bouncing problems?

Thanks,

Bart.





  parent reply	other threads:[~2018-02-08 15:25 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-02-05 15:20 [PATCH V2 0/8] blk-mq/scsi-mq: support global tags & introduce force_blk_mq Ming Lei
2018-02-05 15:20 ` [PATCH V2 1/8] blk-mq: tags: define several fields of tags as pointer Ming Lei
2018-02-06 21:41   ` Omar Sandoval
2018-02-05 15:20 ` [PATCH V2 2/8] blk-mq: introduce BLK_MQ_F_GLOBAL_TAGS Ming Lei
2018-02-06 20:33   ` Omar Sandoval
2018-02-07  0:44     ` Ming Lei
2018-02-06 23:18   ` Jens Axboe
2018-02-07  0:43     ` Ming Lei
2018-02-07 16:09     ` Bart Van Assche
2018-02-07 16:59   ` Bart Van Assche
2018-02-07 16:59     ` Bart Van Assche
2018-02-08 15:25   ` Bart Van Assche [this message]
2018-02-08 15:25     ` Bart Van Assche
2018-02-05 15:20 ` [PATCH V2 3/8] scsi: Add template flag 'host_tagset' Ming Lei
2018-02-05 15:20 ` [PATCH V2 4/8] block: null_blk: introduce module parameter of 'g_global_tags' Ming Lei
2018-02-05 20:26   ` Don Brace
2018-02-05 20:26     ` Don Brace
2018-02-06 21:43   ` Omar Sandoval
2018-02-05 15:20 ` [PATCH V2 5/8] scsi: introduce force_blk_mq Ming Lei
2018-02-06 20:20   ` Omar Sandoval
2018-02-07  0:46     ` Ming Lei
2018-02-05 15:20 ` [PATCH V2 6/8] scsi: virtio_scsi: fix IO hang by irq vector automatic affinity Ming Lei
2018-02-05 15:56   ` Paolo Bonzini
2018-02-05 15:20 ` [PATCH V2 7/8] scsi: hpsa: call hpsa_hba_inquiry() after adding host Ming Lei
2018-02-05 18:55   ` Don Brace
2018-02-05 18:55     ` Don Brace
2018-02-06  8:32   ` Hannes Reinecke
2018-02-05 15:20 ` [PATCH V2 8/8] scsi: hpsa: use blk_mq to solve irq affinity issue Ming Lei
2018-02-05 15:58   ` Laurence Oberman
2018-02-05 15:58     ` Laurence Oberman
2018-02-05 16:07     ` Don Brace
2018-02-05 16:07       ` Don Brace
2018-02-05 18:54     ` Don Brace
2018-02-05 18:54       ` Don Brace
2018-02-06  2:18   ` chenxiang (M)
2018-02-06  2:18     ` chenxiang (M)
2018-02-06  8:23     ` Ming Lei
2018-02-06  8:39   ` Hannes Reinecke
2018-02-06  9:51     ` Ming Lei
2018-02-06 23:15 ` [PATCH V2 0/8] blk-mq/scsi-mq: support global tags & introduce force_blk_mq Jens Axboe

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