From: Keith Busch <keith.busch@intel.com>
To: John Garry <john.garry@huawei.com>
Cc: "tglx@linutronix.de" <tglx@linutronix.de>,
Christoph Hellwig <hch@lst.de>,
Marc Zyngier <marc.zyngier@arm.com>,
"axboe@kernel.dk" <axboe@kernel.dk>,
Peter Zijlstra <peterz@infradead.org>,
Michael Ellerman <mpe@ellerman.id.au>,
Linuxarm <linuxarm@huawei.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Hannes Reinecke <hare@suse.com>
Subject: Re: Question on handling managed IRQs when hotplugging CPUs
Date: Tue, 29 Jan 2019 10:20:59 -0700 [thread overview]
Message-ID: <20190129172059.GC17132@localhost.localdomain> (raw)
In-Reply-To: <757902fc-a9ea-090b-7853-89944a0ce1b5@huawei.com>
On Tue, Jan 29, 2019 at 05:12:40PM +0000, John Garry wrote:
> On 29/01/2019 15:44, Keith Busch wrote:
> >
> > Hm, we used to freeze the queues with CPUHP_BLK_MQ_PREPARE callback,
> > which would reap all outstanding commands before the CPU and IRQ are
> > taken offline. That was removed with commit 4b855ad37194f ("blk-mq:
> > Create hctx for each present CPU"). It sounds like we should bring
> > something like that back, but make more fine grain to the per-cpu context.
> >
>
> Seems reasonable. But we would need it to deal with drivers where they only
> expose a single queue to BLK MQ, but use many queues internally. I think
> megaraid sas does this, for example.
>
> I would also be slightly concerned with commands being issued from the
> driver unknown to blk mq, like SCSI TMF.
I don't think either of those descriptions sound like good candidates
for using managed IRQ affinities.
next prev parent reply other threads:[~2019-01-29 17:21 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-29 11:25 Question on handling managed IRQs when hotplugging CPUs John Garry
2019-01-29 11:54 ` Hannes Reinecke
2019-01-29 12:01 ` Thomas Gleixner
2019-01-29 15:27 ` John Garry
2019-01-29 16:27 ` Thomas Gleixner
2019-01-29 17:23 ` John Garry
2019-01-29 15:44 ` Keith Busch
2019-01-29 17:12 ` John Garry
2019-01-29 17:20 ` Keith Busch [this message]
2019-01-30 10:38 ` John Garry
2019-01-30 12:43 ` Thomas Gleixner
2019-01-31 17:48 ` John Garry
2019-02-01 15:56 ` Hannes Reinecke
2019-02-01 21:57 ` Thomas Gleixner
2019-02-04 7:12 ` Hannes Reinecke
2019-02-05 13:24 ` John Garry
2019-02-05 14:52 ` Keith Busch
2019-02-05 15:09 ` John Garry
2019-02-05 15:11 ` Keith Busch
2019-02-05 15:15 ` Hannes Reinecke
2019-02-05 15:27 ` John Garry
2019-02-05 18:23 ` Christoph Hellwig
2019-02-06 9:21 ` John Garry
2019-02-06 13:34 ` Benjamin Block
2019-02-05 15:10 ` Hannes Reinecke
2019-02-05 15:16 ` Keith Busch
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