From: Ming Lei <ming.lei@redhat.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org, John Garry <john.garry@huawei.com>,
Bart Van Assche <bvanassche@acm.org>,
Hannes Reinecke <hare@suse.com>,
Thomas Gleixner <tglx@linutronix.de>,
will@kernel.org, peterz@infradead.org, paulmck@kernel.org
Subject: Re: [PATCH V8 07/11] blk-mq: stop to handle IO and drain IO before hctx becomes inactive
Date: Tue, 28 Apr 2020 09:10:14 +0800 [thread overview]
Message-ID: <20200428011014.GA603273@T590> (raw)
In-Reply-To: <20200427153601.GA7802@lst.de>
On Mon, Apr 27, 2020 at 05:36:01PM +0200, Christoph Hellwig wrote:
> On Sun, Apr 26, 2020 at 10:06:21AM +0800, Ming Lei wrote:
> > On Sat, Apr 25, 2020 at 05:48:32PM +0200, Christoph Hellwig wrote:
> > > FYI, here is what I think we should be doing (but the memory model
> > > experts please correct me):
> > >
> > > - just drop the direct_issue flag and check for the CPU, which is
> > > cheap enough
> >
> > That isn't correct because the CPU for running async queue may not be
> > same with rq->mq_ctx->cpu since hctx->cpumask may include several CPUs
> > and we run queue in RR style and it is really a normal case.
>
> But in that case the memory barrier really doesn't matter anywaẏ.
It might be true, however we can save the cost with zero cost, why
not do it? Also with document benefit.
Thanks,
Ming
next prev parent reply other threads:[~2020-04-28 1:10 UTC|newest]
Thread overview: 80+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-24 10:23 [PATCH V8 00/11] blk-mq: improvement CPU hotplug Ming Lei
2020-04-24 10:23 ` [PATCH V8 01/11] block: clone nr_integrity_segments and write_hint in blk_rq_prep_clone Ming Lei
2020-04-24 10:32 ` Christoph Hellwig
2020-04-24 12:43 ` Hannes Reinecke
2020-04-24 16:11 ` Martin K. Petersen
2020-04-24 10:23 ` [PATCH V8 02/11] block: add helper for copying request Ming Lei
2020-04-24 10:35 ` Christoph Hellwig
2020-04-24 12:43 ` Hannes Reinecke
2020-04-24 16:12 ` Martin K. Petersen
2020-04-24 10:23 ` [PATCH V8 03/11] blk-mq: mark blk_mq_get_driver_tag as static Ming Lei
2020-04-24 12:44 ` Hannes Reinecke
2020-04-24 16:13 ` Martin K. Petersen
2020-04-24 10:23 ` [PATCH V8 04/11] blk-mq: assign rq->tag in blk_mq_get_driver_tag Ming Lei
2020-04-24 10:35 ` Christoph Hellwig
2020-04-24 13:02 ` Hannes Reinecke
2020-04-25 2:54 ` Ming Lei
2020-04-25 18:26 ` Hannes Reinecke
2020-04-24 10:23 ` [PATCH V8 05/11] blk-mq: support rq filter callback when iterating rqs Ming Lei
2020-04-24 13:17 ` Hannes Reinecke
2020-04-25 3:04 ` Ming Lei
2020-04-24 10:23 ` [PATCH V8 06/11] blk-mq: prepare for draining IO when hctx's all CPUs are offline Ming Lei
2020-04-24 13:23 ` Hannes Reinecke
2020-04-25 3:24 ` Ming Lei
2020-04-24 10:23 ` [PATCH V8 07/11] blk-mq: stop to handle IO and drain IO before hctx becomes inactive Ming Lei
2020-04-24 10:38 ` Christoph Hellwig
2020-04-25 3:17 ` Ming Lei
2020-04-25 8:32 ` Christoph Hellwig
2020-04-25 9:34 ` Ming Lei
2020-04-25 9:53 ` Ming Lei
2020-04-25 15:48 ` Christoph Hellwig
2020-04-26 2:06 ` Ming Lei
2020-04-26 8:19 ` John Garry
2020-04-27 15:36 ` Christoph Hellwig
2020-04-28 1:10 ` Ming Lei [this message]
2020-04-27 19:03 ` Paul E. McKenney
2020-04-28 6:54 ` Christoph Hellwig
2020-04-28 15:58 ` Peter Zijlstra
2020-04-29 2:16 ` Ming Lei
2020-04-29 8:07 ` Will Deacon
2020-04-29 9:46 ` Ming Lei
2020-04-29 12:27 ` Will Deacon
2020-04-29 13:43 ` Ming Lei
2020-04-29 17:34 ` Will Deacon
2020-04-30 0:39 ` Ming Lei
2020-04-30 11:04 ` Will Deacon
2020-04-30 14:02 ` Ming Lei
2020-05-05 15:46 ` Christoph Hellwig
2020-05-06 1:24 ` Ming Lei
2020-05-06 7:28 ` Will Deacon
2020-05-06 8:07 ` Ming Lei
2020-05-06 9:56 ` Will Deacon
2020-05-06 10:22 ` Ming Lei
2020-04-29 17:46 ` Paul E. McKenney
2020-04-30 0:43 ` Ming Lei
2020-04-24 13:27 ` Hannes Reinecke
2020-04-25 3:30 ` Ming Lei
2020-04-24 13:42 ` John Garry
2020-04-25 3:41 ` Ming Lei
2020-04-24 10:23 ` [PATCH V8 08/11] block: add blk_end_flush_machinery Ming Lei
2020-04-24 10:41 ` Christoph Hellwig
2020-04-25 3:44 ` Ming Lei
2020-04-25 8:11 ` Christoph Hellwig
2020-04-25 9:51 ` Ming Lei
2020-04-24 13:47 ` Hannes Reinecke
2020-04-25 3:47 ` Ming Lei
2020-04-24 10:23 ` [PATCH V8 09/11] blk-mq: add blk_mq_hctx_handle_dead_cpu for handling cpu dead Ming Lei
2020-04-24 10:42 ` Christoph Hellwig
2020-04-25 3:48 ` Ming Lei
2020-04-24 13:48 ` Hannes Reinecke
2020-04-24 10:23 ` [PATCH V8 10/11] blk-mq: re-submit IO in case that hctx is inactive Ming Lei
2020-04-24 10:44 ` Christoph Hellwig
2020-04-25 3:52 ` Ming Lei
2020-04-24 13:55 ` Hannes Reinecke
2020-04-25 3:59 ` Ming Lei
2020-04-24 10:23 ` [PATCH V8 11/11] block: deactivate hctx when the hctx is actually inactive Ming Lei
2020-04-24 10:43 ` Christoph Hellwig
2020-04-24 13:56 ` Hannes Reinecke
2020-04-24 15:23 ` [PATCH V8 00/11] blk-mq: improvement CPU hotplug Jens Axboe
2020-04-24 15:40 ` Christoph Hellwig
2020-04-24 15:41 ` Jens Axboe
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