From: Thomas Gleixner <tglx@linutronix.de>
To: Rik van Riel <riel@redhat.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Frederic Weisbecker <fweisbec@gmail.com>,
Chris Metcalf <cmetcalf@ezchip.com>,
Christoph Lameter <cl@linux.com>
Subject: Re: [PATCH] genirq: Add default affinity mask command line option
Date: Wed, 3 Feb 2016 20:15:15 +0100 (CET) [thread overview]
Message-ID: <alpine.DEB.2.11.1602032013060.25254@nanos> (raw)
In-Reply-To: <56B25116.5040809@redhat.com>
On Wed, 3 Feb 2016, Rik van Riel wrote:
> On 02/03/2016 01:52 PM, Thomas Gleixner wrote:
> > From: Thomas Gleixner <tglx@linutronix.de> Date: Fri May 25
> > 16:59:47 2012 +0200 Subject: genirq: Add default affinity mask
> > command line option
> >
> > If we isolate CPUs, then we don't want random device interrupts on
> > them. Even w/o the user space irq balancer enabled we can end up
> > with irqs on non boot cpus and chasing newly requested interrupts
> > is a tedious task.
>
> The userspace irqbalance daemon has code nowadays to prevent
> it from putting irqs on isolated CPUs.
I know, but a lot of systems do not enable it at all.
> > Allow to restrict the default irq affinity mask.
>
> However, not placing them on there at boot time is a great
> enhancement, too.
That's the main plan :)
> Would it make sense to key off the isolated_cpus mask
> if isolated_cpus= was specified, but no irqaffinity
> mask was specified?
That might be an add on.
> Is there any use case where we would want irqs on
> isolated cpus by default, and could not bear the
> cost of reassigning them from userspace after boot?
I don't think so. Those interrupts you want on an isolated cpu are obviously
hand selected.
Thanks,
tglx
next prev parent reply other threads:[~2016-02-03 19:16 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-03 18:52 [PATCH] genirq: Add default affinity mask command line option Thomas Gleixner
2016-02-03 19:12 ` Rik van Riel
2016-02-03 19:15 ` Thomas Gleixner [this message]
2016-02-08 10:50 ` [tip:irq/core] " tip-bot for Thomas Gleixner
2016-02-08 14:08 ` tip-bot for Thomas Gleixner
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