From: Christoph Hellwig <hch@lst.de>
To: Ming Lei <ming.lei@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>, 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 11:46:18 +0200 [thread overview]
Message-ID: <20210429094618.GA15311@lst.de> (raw)
In-Reply-To: <YIpiS0d1NeoX6p0H@T590>
On Thu, Apr 29, 2021 at 03:37:47PM +0800, Ming Lei wrote:
> > > 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().
The all drivers setting it have a problem, as the blk-mq core sets
BLK_MQ_F_BLOCKING for all of them. The right fix would be to not make
it block for REQ_NOWAIT I/O..
next prev parent reply other threads:[~2021-04-29 9:46 UTC|newest]
Thread overview: 28+ 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
2021-04-29 9:46 ` Christoph Hellwig [this message]
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
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