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Date: Mon, 28 Aug 2017 10:38:01 -0500 (CDT)
From: Christopher Lameter <cl@linux.com>
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To: Peter Zijlstra <peterz@infradead.org>
cc: Frederic Weisbecker <fweisbec@gmail.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Chris Metcalf <cmetcalf@mellanox.com>,
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        Luiz Capitulino <lcapitulino@redhat.com>,
        "Paul E . McKenney" <paulmck@linux.vnet.ibm.com>,
        Ingo Molnar <mingo@kernel.org>, Mike Galbraith <efault@gmx.de>,
        Rik van Riel <riel@redhat.com>, Wanpeng Li <kernellwp@gmail.com>
Subject: Re: [RFC PATCH 12/12] housekeeping: Reimplement isolcpus on
 housekeeping
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On Mon, 28 Aug 2017, Peter Zijlstra wrote:

> > I think that change is good maybe even a bugfix. I had some people be very
> > surprised when they set affinities to multiple cpus and the processeds
> > kept sticking to one cpu because of isolcpus.
>
> Those people cannot read. And no its not a bug fix. Its documented and
> intended behaviour.

Well the next step was to create a cgroup with those processors and
suddenly load balancing worked again.

This is all pretty confusing stuff. I would rather get rid of isolcpus and
rely on the process affinities set to a single processor, and the removal
of the this processor from all other processes as a sufficient.

I think this already does the right thing. What is mentioned in the isolcpus
documentation is a worry about "suboptimal scheduler performance".

Could we address that issue (if it is still there) and then get rid of
isolcpus?