1. 06 Nov, 2015 1 commit
  2. 25 Jun, 2015 1 commit
    • Chris Metcalf's avatar
      watchdog: add watchdog_cpumask sysctl to assist nohz · fe4ba3c3
      Chris Metcalf authored
      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: default avatarChris Metcalf <cmetcalf@ezchip.com>
      Acked-by: default avatarDon 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: default avatarJohn Hubbard <jhubbard@nvidia.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      fe4ba3c3
  3. 26 Aug, 2014 1 commit
  4. 11 Feb, 2012 1 commit