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From: Thomas Gleixner <tglx@linutronix.de>
To: Ming Lei <ming.lei@redhat.com>
Cc: Artem Bityutskiy <dedekind1@gmail.com>,
	Jens Axboe <axboe@kernel.dk>,
	Christoph Hellwig <hch@infradead.org>,
	linux-kernel@vger.kernel.org, linux-block@vger.kernel.org,
	Laurence Oberman <loberman@redhat.com>
Subject: Re: [PATCH V3 0/4] genirq/affinity: irq vector spread among online CPUs as far as possible
Date: Fri, 9 Mar 2018 11:08:54 +0100 (CET)	[thread overview]
Message-ID: <alpine.DEB.2.21.1803091107520.1364@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20180309012458.GD5228@ming.t460p>

On Fri, 9 Mar 2018, Ming Lei wrote:
> On Fri, Mar 09, 2018 at 12:20:09AM +0100, Thomas Gleixner wrote:
> > On Thu, 8 Mar 2018, Ming Lei wrote:
> > > Actually, it isn't a real fix, the real one is in the following two:
> > > 
> > > 	0c20244d458e scsi: megaraid_sas: fix selection of reply queue
> > > 	ed6d043be8cd scsi: hpsa: fix selection of reply queue
> > 
> > Where are these commits? Neither Linus tree not -next know anything about
> > them....
> 
> Both aren't merged yet, but they should land V4.16, IMO.
> 
> > 
> > > This patchset can't guarantee that all IRQ vectors are assigned by one
> > > online CPU, for example, in a quad-socket system, if only one processor
> > > is present, then some of vectors are still assigned by all offline CPUs,
> > > and it is a valid case, but still may cause io hang if drivers(hpsa,
> > > megaraid_sas) select reply queue in current way.
> > 
> > So my understanding is that these irq patches are enhancements and not bug
> > fixes. I'll queue them for 4.17 then.
> 
> Wrt. this IO hang issue, these patches shouldn't be bug fix, but they may
> fix performance regression[1] for some systems caused by 84676c1f21 ("genirq/affinity:
> assign vectors to all possible CPUs").
> 
> [1] https://marc.info/?l=linux-block&m=152050347831149&w=2

Hmm. The patches are rather large for urgent and evtl. backporting. Is
there a simpler way to address that performance issue?

Thanks,

	tglx

  parent reply	other threads:[~2018-03-09 10:08 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-08 10:53 [PATCH V3 0/4] genirq/affinity: irq vector spread among online CPUs as far as possible Ming Lei
2018-03-08 10:53 ` [PATCH V3 1/4] genirq/affinity: rename *node_to_possible_cpumask as *node_to_cpumask Ming Lei
2018-04-06 21:52   ` [tip:irq/core] genirq/affinity: Rename " tip-bot for Ming Lei
2018-03-08 10:53 ` [PATCH V3 2/4] genirq/affinity: move actual irq vector spread into one helper Ming Lei
2018-04-06 21:53   ` [tip:irq/core] genirq/affinity: Move actual irq vector spreading into a helper function tip-bot for Ming Lei
2018-03-08 10:53 ` [PATCH V3 3/4] genirq/affinity: support to do irq vectors spread starting from any vector Ming Lei
2018-04-06 21:53   ` [tip:irq/core] genirq/affinity: Allow irq spreading from a given starting point tip-bot for Ming Lei
2018-03-08 10:53 ` [PATCH V3 4/4] genirq/affinity: irq vector spread among online CPUs as far as possible Ming Lei
2018-04-03 13:32   ` Thomas Gleixner
2018-04-03 16:00     ` Ming Lei
2018-04-04  8:25       ` Thomas Gleixner
2018-04-04 12:45         ` Thomas Gleixner
2018-04-04 15:20           ` Ming Lei
2018-04-05 10:12             ` Thomas Gleixner
2018-04-04 15:08         ` Ming Lei
2018-04-04 19:38           ` Thomas Gleixner
2018-04-06  9:13             ` Ming Lei
2018-04-06  9:46               ` Thomas Gleixner
2018-04-06 21:49                 ` Thomas Gleixner
2018-04-08  3:19                   ` Ming Lei
2018-04-06 21:54   ` [tip:irq/core] genirq/affinity: Spread irq vectors among present " tip-bot for Ming Lei
2018-03-08 13:18 ` [PATCH V3 0/4] genirq/affinity: irq vector spread among online " Artem Bityutskiy
2018-03-08 13:25   ` Artem Bityutskiy
2018-03-08 13:34   ` Ming Lei
2018-03-08 23:20     ` Thomas Gleixner
2018-03-09  1:24       ` Ming Lei
2018-03-09  7:00         ` Artem Bityutskiy
2018-03-09  7:33           ` Ming Lei
2018-03-09 10:08         ` Thomas Gleixner [this message]
2018-03-09 12:08           ` Ming Lei
2018-03-09 15:08             ` Thomas Gleixner
2018-03-13  3:11               ` Dou Liyang
2018-03-13  7:38                 ` Artem Bityutskiy
2018-03-13  7:38                   ` Artem Bityutskiy
2018-03-13  8:35                   ` Ming Lei
2018-03-13  8:39                     ` Artem Bityutskiy
2018-03-13  8:39                       ` Artem Bityutskiy
2018-03-13  9:35                       ` Rafael J. Wysocki
2018-03-14  3:29                         ` Dou Liyang
2018-03-14  4:11                           ` Dou Liyang
2018-03-14  9:07                             ` Artem Bityutskiy
2018-03-14  9:47                               ` Dou Liyang
2018-03-13  9:25                 ` Rafael J. Wysocki
2018-03-14  3:30                   ` Dou Liyang
2018-03-30  3:15               ` Ming Lei
2018-04-03 12:55                 ` Thomas Gleixner
2018-03-26  8:39   ` Thorsten Leemhuis
2018-03-28  6:15     ` Artem Bityutskiy

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