From: Christoph Hellwig <hch@lst.de>
To: Ming Lei <ming.lei@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org, linux-scsi@vger.kernel.org,
linux-nvme@lists.infradead.org
Subject: Re: sorting out the freeze / quiesce mess
Date: Wed, 10 Nov 2021 13:58:56 +0100 [thread overview]
Message-ID: <20211110125856.GA25614@lst.de> (raw)
In-Reply-To: <YYuQ9mhHtDNDVFQ3@T590>
On Wed, Nov 10, 2021 at 05:29:26PM +0800, Ming Lei wrote:
> On Wed, Nov 10, 2021 at 10:14:07AM +0100, Christoph Hellwig wrote:
> > Hi Jens and Ming,
> >
> > I've been looking into properly supporting queue freezing for bio based
> > drivers (that is only release q_usage_counter on bio completion for them).
> > And the deeper I look into the code the more I'm confused by us having
> > the blk_mq_quiesce* interface in addition to blk_freeze_queue. What
> > is a good reason to do a quiesce separately from a freeze?
>
> freeze can make sure that all requests are done, quiesce can make sure that
> dispatch critical area(covered by hctx lock/unlock) is done.
Yeah, but why do we need to still call quiesce after we just did a
freeze, which is about half of the users?
next prev parent reply other threads:[~2021-11-10 12:59 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-10 9:14 sorting out the freeze / quiesce mess Christoph Hellwig
2021-11-10 9:29 ` Ming Lei
2021-11-10 9:52 ` Ming Lei
2021-11-10 12:58 ` Christoph Hellwig [this message]
2021-11-10 14:56 ` Ming Lei
2021-11-10 10:22 ` Hannes Reinecke
2021-11-10 10:45 ` Ming Lei
2021-11-10 12:32 ` James Bottomley
2021-11-10 13:30 ` Max Gurtovoy
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