All of lore.kernel.org
 help / color / mirror / Atom feed
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..

  reply	other threads:[~2021-04-29  9:46 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
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
2021-05-12 13:15   ` Christoph Hellwig

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210429094618.GA15311@lst.de \
    --to=hch@lst.de \
    --cc=Damien.LeMoal@wdc.com \
    --cc=anil.vasudevan@intel.com \
    --cc=axboe@kernel.dk \
    --cc=jefflexu@linux.alibaba.com \
    --cc=kbusch@kernel.org \
    --cc=linux-block@vger.kernel.org \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=mark.wunderlich@intel.com \
    --cc=ming.lei@redhat.com \
    --cc=sagi@grimberg.me \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.