• Frederic Weisbecker's avatar
    watchdog: Boot-disable by default on full dynticks · 940be35a
    Frederic Weisbecker authored
    When the watchdog runs, it prevents the full dynticks
    CPUs from stopping their tick because the hard lockup
    detector uses perf events internally, which in turn
    rely on the periodic tick.
    
    Since this is a rather confusing behaviour that is not
    easy to track down and identify for those who want to
    test CONFIG_NO_HZ_FULL, let's default disable the
    watchdog on boot time when full dynticks is enabled.
    
    The user can still enable it later on runtime using
    proc or sysctl.
    Reported-by: default avatarSteven Rostedt <rostedt@goodmis.org>
    Suggested-by: default avatarPeter Zijlstra <peterz@infradead.org>
    Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
    Cc: Steven Rostedt <rostedt@goodmis.org>
    Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
    Cc: Ingo Molnar <mingo@kernel.org>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Li Zhong <zhong@linux.vnet.ibm.com>
    Cc: Don Zickus <dzickus@redhat.com>
    Cc: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
    Cc: Anish Singh <anish198519851985@gmail.com>
    940be35a
watchdog.c 14.4 KB