linux-kernel - Re: [PATCH] affine kernel threads to specified cpumask

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Message-ID: <20200324113829.GA16502@fuller.cnet>
Date:   Tue, 24 Mar 2020 08:38:29 -0300
From:   Marcelo Tosatti <mtosatti@...hat.com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     Chris Friesen <chris.friesen@...driver.com>,
        linux-kernel@...r.kernel.org, Christoph Lameter <cl@...ux.com>,
        Vu Tran <vu.tran@...driver.com>,
        Jim Somerville <Jim.Somerville@...driver.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Frederic Weisbecker <fweisbec@...il.com>,
        Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH] affine kernel threads to specified cpumask

On Mon, Mar 23, 2020 at 09:31:59PM +0100, Thomas Gleixner wrote:
> Chris,
> 
> Chris Friesen <chris.friesen@...driver.com> writes:
> > On 3/23/2020 10:22 AM, Thomas Gleixner wrote:
> >> Marcelo Tosatti <mtosatti@...hat.com> writes:
> >>> This allows CPU isolation (that is not allowing certain threads
> >>> to execute on certain CPUs) without using the isolcpus= parameter,
> >>> making it possible to enable load balancing on such CPUs
> >>> during runtime.
> >> 
> >> I'm surely missing some background information, but that sentence does
> >> not make any sense to me.
> >
> > The idea is to affine general kernel threads to specific "housekeeping" 
> > CPUs, while still allowing load balancing of tasks.
> >
> > The isolcpus= boot parameter would prevent kernel threads from running 
> > on the isolated CPUs, but it disables load balancing on the isolated CPUs.
> 
> So why can't we just have a isolcpus mode which allows that instead of
> adding more command line options which are slightly different?
> 
> We just added some magic for managed interrupts to isolcpus, which is
> surely interesting for your scenario as well...
> 
> Thanks,
> 
>         tglx

Hi Thomas, Chris,

Works for me, will adjust and resend.