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From: Sagi Grimberg <sagi@grimberg.me>
To: Hannes Reinecke <hare@suse.de>, Christoph Hellwig <hch@lst.de>,
	Keith Busch <kbusch@kernel.org>, Jens Axboe <axboe@kernel.dk>
Cc: Chao Leng <lengchao@huawei.com>,
	linux-block@vger.kernel.org, linux-nvme@lists.infradead.org
Subject: Re: [PATCH 2/2] nvme-multipath: don't block on blk_queue_enter of the underlying device
Date: Tue, 23 Mar 2021 00:31:32 -0700	[thread overview]
Message-ID: <608f8198-8c0d-b59c-180b-51666840382d@grimberg.me> (raw)
In-Reply-To: <c064b296-c25c-3731-cbbd-f99ab93e6bd2@suse.de>


> Actually, I had been playing around with marking the entire bio as 
> 'NOWAIT'; that would avoid the tag stall, too:
> 
> @@ -313,7 +316,7 @@ blk_qc_t nvme_ns_head_submit_bio(struct bio *bio)
>          ns = nvme_find_path(head);
>          if (likely(ns)) {
>                  bio_set_dev(bio, ns->disk->part0);
> -               bio->bi_opf |= REQ_NVME_MPATH;
> +               bio->bi_opf |= REQ_NVME_MPATH | REQ_NOWAIT;
>                  trace_block_bio_remap(bio, disk_devt(ns->head->disk),
>                                        bio->bi_iter.bi_sector);
>                  ret = submit_bio_noacct(bio);
> 
> 
> My only worry here is that we might incur spurious failures under high 
> load; but then this is not necessarily a bad thing.

What? making spurious failures is not ok under any load. what fs will
take into account that you may have run out of tags?

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  reply	other threads:[~2021-03-23  7:31 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-22  7:37 fix nvme-tcp and nvme-rdma controller reset hangs when using multipath Christoph Hellwig
2021-03-22  7:37 ` [PATCH 1/2] blk-mq: add a blk_mq_submit_bio_direct API Christoph Hellwig
2021-03-22 11:23   ` Hannes Reinecke
2021-03-22 15:30   ` Keith Busch
2021-03-22  7:37 ` [PATCH 2/2] nvme-multipath: don't block on blk_queue_enter of the underlying device Christoph Hellwig
2021-03-22 11:22   ` Hannes Reinecke
2021-03-22 15:31   ` Keith Busch
2021-03-23  2:57   ` Sagi Grimberg
2021-03-23  3:23     ` Sagi Grimberg
2021-03-23  7:04       ` Chao Leng
2021-03-23  7:36         ` Sagi Grimberg
2021-03-23  8:13           ` Chao Leng
2021-03-23 16:17             ` Christoph Hellwig
2021-03-23 16:15           ` Christoph Hellwig
2021-03-23 18:13             ` Sagi Grimberg
2021-03-23 18:22               ` Christoph Hellwig
2021-03-23 19:00                 ` Sagi Grimberg
2021-03-23 19:01                   ` Christoph Hellwig
2021-03-23 19:10                     ` Sagi Grimberg
2021-03-23  7:28     ` Hannes Reinecke
2021-03-23  7:31       ` Sagi Grimberg [this message]
2021-03-23  8:36         ` Hannes Reinecke
2021-03-23 14:53           ` Keith Busch
2021-03-23 16:19             ` Christoph Hellwig

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