linux-kernel - Re: [RFC] Restrict kernel spawning of threads to a specified set of cpus.

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Message-ID: <20130912143137.GA23839@somewhere>
Date:	Thu, 12 Sep 2013 16:31:38 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Christoph Lameter <cl@...ux.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Gilad Ben-Yossef <gilad@...yossef.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Mike Frysinger <vapier@...too.org>,
	linux-kernel@...r.kernel.org,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: Re: [RFC] Restrict kernel spawning of threads to a specified set of
 cpus.

On Thu, Sep 12, 2013 at 02:22:43PM +0000, Christoph Lameter wrote:
> On Thu, 12 Sep 2013, Frederic Weisbecker wrote:
> 
> > On Thu, Sep 12, 2013 at 02:10:56PM +0000, Christoph Lameter wrote:
> > > On Thu, 12 Sep 2013, Frederic Weisbecker wrote:
> > >
> > > > Why not do this from userspace instead?
> > >
> > > Because the cpumasks are hardcoded in the kernel code.
> > >
> >
> > Ok but you can change the affinity of a kthread from userspace, as
> > long as you define a cpu set that is among that kthread's cpus allowed.
> 
> Ok but at that point kthread has already spawned a lot of kernel threads.
> 
> The same is true for init and kmod.
> 

Ok but then we just need to set the affinity of all these kthreads.
A simple lookup on /proc/[0-9]+/ should do the trick.
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