On Mon, 14 Dec 2015 10:26:07 -0800
Stephen Hemminger <stephen at networkplumber.org> wrote:
> From: "Charles (Chas) Williams" <ciwillia at brocade.com>
>
> A NO_HZ_FULL kernel needs to have a stable clock source like a non-stop
> (or invariant) TSC. Unfortunately, this CPU feature/flag isn't advertised
> by most hypervisors because they want the ability to migrate or save
> virtual machines which would affect the TSC.
>
> This means that a kernel with NO_HZ_FULL configured would often generate
> a kernel traceback on boot which causes users to generate false
> alarms. NO_HZ_FULL is an optimization not a hard requirement.
> Keep the message, just lose the traceback.
>
> Signed-off-by: Charles (Chas) Williams <ciwillia at brocade.com>
> Signed-off-by: Stephen Hemminger <stephen at networkplumber.org>
> ---
> kernel/time/tick-sched.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
> index 7c7ec45..2e1c90c 100644
> --- a/kernel/time/tick-sched.c
> +++ b/kernel/time/tick-sched.c
> @@ -188,8 +188,8 @@ static bool can_stop_full_tick(void)
> * Don't allow the user to think they can get
> * full NO_HZ with this machine.
> */
> - WARN_ONCE(tick_nohz_full_running,
> - "NO_HZ FULL will not work with unstable sched clock");
> + if (tick_nohz_full_running)
> + pr_notice_once("NO_HZ FULL will not work with unstable
> sched clock\n");
> return false;
> }
> #endif
Never mind, wrong list
