Re: [PATCH v9 1/3] smpboot: allow excluding cpus from the smpboot threads

From: Chris Metcalf
Date: Thu Apr 30 2015 - 12:07:39 EST

On 04/29/2015 06:26 PM, Andrew Morton wrote:
On Fri, 17 Apr 2015 14:37:16 -0400 Chris Metcalf <cmetcalf@xxxxxxxxxx> wrote:

This change allows some cores to be excluded from running the
smp_hotplug_thread tasks. The following commit to update
kernel/watchdog.c to use this functionality is the motivating
example, and more information on the motivation is provided there.

A new smp_hotplug_thread field is introduced, "cpumask", which
is cpumask field managed by the smpboot subsystem that indicates whether
or not the given smp_hotplug_thread should run on that core; the
cpumask is checked when deciding whether to unpark the thread.

To limit the cpumask to less than cpu_possible, you must call
smpboot_update_cpumask_percpu_thread() after registering.
Has Thomas commented on any version of this? t'would be nice.

He offered some specific feedback here:

that I reflected in the subsequent iteration of the patch series.

Thomas, any additional feedback would be appreciated.

Chris Metcalf, EZChip Semiconductor

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