From: Daniel Bristot de Oliveira <daniel@bristot.me>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Mathias Koehrer <mathias.koehrer@etas.com>
Cc: "linux-rt-users@vger.kernel.org" <linux-rt-users@vger.kernel.org>
Subject: Re: Kernel thread's CPU affinity with isolcpus kernel boot argument
Date: Thu, 25 Feb 2016 12:13:46 -0300 [thread overview]
Message-ID: <56CF1A2A.1050203@bristot.me> (raw)
In-Reply-To: <20160225141806.GB16161@linutronix.de>
On 02/25/2016 11:18 AM, Sebastian Andrzej Siewior wrote:
> not that I am aware of. There are a few per-CPU threads which have to
> stay the way they are. I would have expected that others like kworker/u*
> respect the isol CPUs and stay away.
Isolcpus is applied only for user-space threads. For instance, you
still need to move rcu offload callbacks away from isolated CPUs, and
all other kernel threads as well.
In the special case of kworker/u* threads, you need to use a special
interface to do it. The interface is the following file:
/sys/devices/virtual/workqueue/cpumask
It was implemented on the following commit:
042f7df workqueue: Allow modifying low level unbound workqueue cpumask
But the default CPU mask is the "cpu_possible_mask".
Sometime ago I sent a patch to modify the default mask of the kworker/u*
threads, to avoid them on isolated CPUs by default, but it was not
acked. It was not explicitly nacked, though.
http://www.gossamer-threads.com/lists/linux/kernel/2218495
Should I try it again?
-- Daniel
next prev parent reply other threads:[~2016-02-25 15:21 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-15 11:15 Kernel thread's CPU affinity with isolcpus kernel boot argument Mathias Koehrer
2016-02-25 14:18 ` Sebastian Andrzej Siewior
2016-02-25 14:43 ` Josh Cartwright
2016-02-26 10:53 ` Mathias Koehrer
2016-02-25 15:13 ` Daniel Bristot de Oliveira [this message]
2016-02-25 16:35 ` Sebastian Andrzej Siewior
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