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From: Christoph Hellwig <[email protected]>
To: Jens Axboe <[email protected]>
Cc: Christoph Hellwig <[email protected]>, Ming Lei <[email protected]>,
	[email protected],
	Thomas Gleixner <[email protected]>,
	[email protected], John Garry <[email protected]>,
	Bart Van Assche <[email protected]>,
	Hannes Reinecke <[email protected]>,
	[email protected]
Subject: Re: io_uring vs CPU hotplug, was Re: [PATCH 5/9] blk-mq: don't set data->ctx and data->hctx in blk_mq_alloc_request_hctx
Date: Wed, 20 May 2020 17:31:23 +0200	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

On Wed, May 20, 2020 at 09:20:50AM -0600, Jens Axboe wrote:
> Just checked, and it works fine for me. If I create an SQPOLL ring with
> SQ_AFF set and bound to CPU 3, if CPU 3 goes offline, then the kthread
> just appears unbound but runs just fine. When CPU 3 comes online again,
> the mask appears correct.
> 
> So don't think there's anything wrong on that side. The affinity is a
> performance optimization, not a correctness issue. Really not much we
> can do if the chosen CPU is offlined, apart from continue to chug along.

Ok, that sounds pretty sensible.

  reply	other threads:[~2020-05-20 15:31 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20200518093155.GB35380@T590>
     [not found] ` <[email protected]>
     [not found]   ` <20200518115454.GA46364@T590>
     [not found]     ` <[email protected]>
     [not found]       ` <20200518141107.GA50374@T590>
     [not found]         ` <[email protected]>
     [not found]           ` <20200519015420.GA70957@T590>
     [not found]             ` <[email protected]>
     [not found]               ` <20200520011823.GA415158@T590>
     [not found]                 ` <20200520030424.GI416136@T590>
2020-05-20  8:03                   ` io_uring vs CPU hotplug, was Re: [PATCH 5/9] blk-mq: don't set data->ctx and data->hctx in blk_mq_alloc_request_hctx Christoph Hellwig
2020-05-20 14:45                     ` Jens Axboe
2020-05-20 15:20                       ` Jens Axboe
2020-05-20 15:31                         ` Christoph Hellwig [this message]
2020-05-20 19:41                         ` Thomas Gleixner
2020-05-20 20:18                           ` Jens Axboe
2020-05-20 22:14                             ` Thomas Gleixner
2020-05-20 22:40                               ` Jens Axboe
2020-05-21  2:27                               ` Ming Lei
2020-05-21  8:13                                 ` Thomas Gleixner
2020-05-21  9:23                                   ` Ming Lei
2020-05-21 18:39                                     ` Thomas Gleixner
2020-05-21 18:45                                       ` Jens Axboe
2020-05-21 20:00                                         ` Thomas Gleixner
2020-05-22  1:57                                       ` Ming Lei

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