diff options
| author | Chris Metcalf <cmetcalf@ezchip.com> | 2015-06-24 16:55:45 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-06-24 17:49:40 -0700 |
| commit | fe4ba3c34352b7e8068b7f18eb233444aed17011 (patch) | |
| tree | d4b34e0d809e784c59eea68cb27c16dc795e371b /include | |
| parent | b5242e98c1cb834feb1e84026f09a4796b49eb4d (diff) | |
| download | linux-fe4ba3c34352b7e8068b7f18eb233444aed17011.tar.bz2 | |
watchdog: add watchdog_cpumask sysctl to assist nohz
Change the default behavior of watchdog so it only runs on the
housekeeping cores when nohz_full is enabled at build and boot time.
Allow modifying the set of cores the watchdog is currently running on
with a new kernel.watchdog_cpumask sysctl.
In the current system, the watchdog subsystem runs a periodic timer that
schedules the watchdog kthread to run. However, nohz_full cores are
designed to allow userspace application code running on those cores to
have 100% access to the CPU. So the watchdog system prevents the
nohz_full application code from being able to run the way it wants to,
thus the motivation to suppress the watchdog on nohz_full cores, which
this patchset provides by default.
However, if we disable the watchdog globally, then the housekeeping
cores can't benefit from the watchdog functionality. So we allow
disabling it only on some cores. See Documentation/lockup-watchdogs.txt
for more information.
[jhubbard@nvidia.com: fix a watchdog crash in some configurations]
Signed-off-by: Chris Metcalf <cmetcalf@ezchip.com>
Acked-by: 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: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/nmi.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/include/linux/nmi.h b/include/linux/nmi.h index 3d46fb4708e0..f94da0e65dea 100644 --- a/include/linux/nmi.h +++ b/include/linux/nmi.h @@ -67,6 +67,7 @@ extern int nmi_watchdog_enabled; extern int soft_watchdog_enabled; extern int watchdog_user_enabled; extern int watchdog_thresh; +extern unsigned long *watchdog_cpumask_bits; extern int sysctl_softlockup_all_cpu_backtrace; struct ctl_table; extern int proc_watchdog(struct ctl_table *, int , @@ -77,6 +78,8 @@ extern int proc_soft_watchdog(struct ctl_table *, int , void __user *, size_t *, loff_t *); extern int proc_watchdog_thresh(struct ctl_table *, int , void __user *, size_t *, loff_t *); +extern int proc_watchdog_cpumask(struct ctl_table *, int, + void __user *, size_t *, loff_t *); #endif #ifdef CONFIG_HAVE_ACPI_APEI_NMI |