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author | Chris Metcalf <cmetcalf@ezchip.com> | 2015-06-24 16:55:42 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-06-24 17:49:40 -0700 |
commit | b5242e98c1cb834feb1e84026f09a4796b49eb4d (patch) | |
tree | 46f415a3fb41a6238f8e6d69675d2e22960c3447 /Documentation/sysctl | |
parent | 8c07a308ec5284fe41aefe48ac2ef4cfcd71ddbf (diff) | |
download | linux-stable-b5242e98c1cb834feb1e84026f09a4796b49eb4d.tar.gz linux-stable-b5242e98c1cb834feb1e84026f09a4796b49eb4d.tar.bz2 linux-stable-b5242e98c1cb834feb1e84026f09a4796b49eb4d.zip |
smpboot: allow excluding cpus from the smpboot threads
This patch series allows the watchdog to run by default only on the
housekeeping cores when nohz_full is in effect; this seems to be a good
compromise short of turning it off completely (since the nohz_full cores
can't tolerate a watchdog).
To provide customizability, we add /proc/sys/kernel/watchdog_cpumask so
that the set of cores running the watchdog can be tuned to different
values after bootup.
To implement this customizability, we add a new
smpboot_update_cpumask_percpu_thread() API to the smpboot_thread
subsystem that lets us park or unpark "unwanted" threads.
And now that threads can be parked for long periods of time, we tweak the
/proc/<pid>/stat and /proc/<pid>/status code so parked threads aren't
reported as running, which is otherwise confusing.
This patch (of 3):
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.
Signed-off-by: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Ulrich Obergfell <uobergfe@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation/sysctl')
0 files changed, 0 insertions, 0 deletions