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From: Ming Lei <ming.lei@redhat.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Jens Axboe <axboe@kernel.dk>,
	Jeffle Xu <jefflexu@linux.alibaba.com>,
	Damien Le Moal <Damien.LeMoal@wdc.com>,
	Keith Busch <kbusch@kernel.org>, Sagi Grimberg <sagi@grimberg.me>,
	"Wunderlich, Mark" <mark.wunderlich@intel.com>,
	"Vasudevan, Anil" <anil.vasudevan@intel.com>,
	linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 14/15] nvme-multipath: set QUEUE_FLAG_NOWAIT
Date: Thu, 29 Apr 2021 15:37:47 +0800	[thread overview]
Message-ID: <YIpiS0d1NeoX6p0H@T590> (raw)
In-Reply-To: <20210429072737.GA3873@lst.de>

On Thu, Apr 29, 2021 at 09:27:37AM +0200, Christoph Hellwig wrote:
> On Wed, Apr 28, 2021 at 10:32:38AM +0800, Ming Lei wrote:
> > > diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
> > > index 4e2c3a6787e9..1d17b2387884 100644
> > > --- a/drivers/nvme/host/multipath.c
> > > +++ b/drivers/nvme/host/multipath.c
> > > @@ -442,6 +442,8 @@ int nvme_mpath_alloc_disk(struct nvme_ctrl *ctrl, struct nvme_ns_head *head)
> > >  	if (!q)
> > >  		goto out;
> > >  	blk_queue_flag_set(QUEUE_FLAG_NONROT, q);
> > > +	blk_queue_flag_set(QUEUE_FLAG_NOWAIT, q);
> > 
> > BLK_MQ_F_BLOCKING is set for nvme-tcp, and the blocking may be done inside
> > nvme_ns_head_submit_bio(), is that one problem?
> 
> The point of BLK_MQ_F_BLOCKING is that ->queue_rq can block, and
> because of that it is not called from the submitting context but in
> a work queue.  nvme-tcp also sets QUEUE_FLAG_NOWAIT, just like all blk-mq
> drivers.

BLK_MQ_F_BLOCKING can be called from submitting context, see
blk_mq_try_issue_directly().



Thanks,
Ming


  reply	other threads:[~2021-04-29  7:37 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-27 16:16 switch block layer polling to a bio based model v2 Christoph Hellwig
2021-04-27 16:16 ` [PATCH 01/15] direct-io: remove blk_poll support Christoph Hellwig
2021-04-27 16:16 ` [PATCH 02/15] block: don't try to poll multi-bio I/Os in __blkdev_direct_IO Christoph Hellwig
2021-04-27 16:16 ` [PATCH 03/15] iomap: don't try to poll multi-bio I/Os in __iomap_dio_rw Christoph Hellwig
2021-04-27 16:16 ` [PATCH 04/15] blk-mq: factor out a blk_qc_to_hctx helper Christoph Hellwig
2021-04-27 16:16 ` [PATCH 05/15] blk-mq: factor out a "classic" poll helper Christoph Hellwig
2021-04-27 16:16 ` [PATCH 06/15] blk-mq: remove blk_qc_t_to_tag and blk_qc_t_is_internal Christoph Hellwig
2021-04-27 16:16 ` [PATCH 07/15] blk-mq: remove blk_qc_t_valid Christoph Hellwig
2021-04-27 16:16 ` [PATCH 08/15] io_uring: don't sleep when polling for I/O Christoph Hellwig
2021-04-27 16:16 ` [PATCH 09/15] block: rename REQ_HIPRI to REQ_POLLED Christoph Hellwig
2021-04-27 16:16 ` [PATCH 10/15] block: use SLAB_TYPESAFE_BY_RCU for the bio slab Christoph Hellwig
2021-04-27 16:16 ` [PATCH 11/15] block: define 'struct bvec_iter' as packed Christoph Hellwig
2021-04-27 16:16 ` [PATCH 12/15] block: switch polling to be bio based Christoph Hellwig
2021-04-28  2:28   ` Ming Lei
2021-04-29  7:20     ` Christoph Hellwig
2021-04-29  7:36       ` Ming Lei
2021-04-29  9:50         ` Christoph Hellwig
2021-04-29 14:42           ` Ming Lei
2021-04-27 16:16 ` [PATCH 13/15] block: add a QUEUE_FLAG_POLL_CAPABLE flag Christoph Hellwig
2021-04-27 16:16 ` [PATCH 14/15] nvme-multipath: set QUEUE_FLAG_NOWAIT Christoph Hellwig
2021-04-28  2:32   ` Ming Lei
2021-04-29  7:27     ` Christoph Hellwig
2021-04-29  7:37       ` Ming Lei [this message]
2021-04-29  9:46         ` Christoph Hellwig
2021-05-06 21:23           ` Sagi Grimberg
2021-04-27 16:16 ` [PATCH 15/15] nvme-multipath: enable polled I/O Christoph Hellwig
2021-04-28  2:36   ` Ming Lei
2021-05-12 13:15 switch block layer polling to a bio based model v3 Christoph Hellwig
2021-05-12 13:15 ` [PATCH 14/15] nvme-multipath: set QUEUE_FLAG_NOWAIT Christoph Hellwig
2021-05-12 13:15   ` Christoph Hellwig

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