this one works, thanks shaohua!
> -----Original Message-----
> From: Li, Shaohua
> Sent: Wednesday, August 31, 2011 9:56 AM
> To: Len Brown
> Cc: Arjan van de Ven; Li, Aubrey; linux acpi
> Subject: [RFC]cpuidle: disable menu governor if nohz is disabled
>
> Lenb,
> Aubrey is asking me to fix the issue. So either we delete disable nohz code or fix
> cpuidle. if you want to fix cpuidle, here it is.
>
> Thanks,
> SHaohua
>
> Subject: cpuidle: disable menu governor if nohz is disabled
>
> Aubrey is asking why nohz disables C-state. nohz has no dependency with idle,
> but menu governor does. If nohz is disabled, using menu governor is pointless,
> because we never get correct sleep length, so let's use ladder governor just like
> nohz isn't compiled in.
>
> Frankly, disabling nohz is strange, but in case somebody cares, here is the fix.
>
> Reported-by: Aubrey Li <aubrey.li@xxxxxxxxx>
> Signed-off-by: Shaohua Li <shaohua.li@xxxxxxxxx>
>
> diff --git a/drivers/cpuidle/governors/menu.c
> b/drivers/cpuidle/governors/menu.c
> index c47f3d0..cbf9afa 100644
> --- a/drivers/cpuidle/governors/menu.c
> +++ b/drivers/cpuidle/governors/menu.c
> @@ -408,6 +408,8 @@ static struct cpuidle_governor menu_governor = {
> */
> static int __init init_menu(void)
> {
> + if (!tick_nohz_enabled)
> + return 0;
> return cpuidle_register_governor(&menu_governor);
> }
>
> diff --git a/include/linux/tick.h b/include/linux/tick.h index b232ccc..88895c7
> 100644
> --- a/include/linux/tick.h
> +++ b/include/linux/tick.h
> @@ -126,6 +126,7 @@ extern void tick_nohz_restart_sched_tick(void);
> extern ktime_t tick_nohz_get_sleep_length(void); extern u64
> get_cpu_idle_time_us(int cpu, u64 *last_update_time); extern u64
> get_cpu_iowait_time_us(int cpu, u64 *last_update_time);
> +extern int tick_nohz_enabled;
> # else
> static inline void tick_nohz_stop_sched_tick(int inidle) { } static inline void
> tick_nohz_restart_sched_tick(void) { } diff --git a/kernel/time/tick-sched.c
> b/kernel/time/tick-sched.c index d5097c4..6a270fe 100644
> --- a/kernel/time/tick-sched.c
> +++ b/kernel/time/tick-sched.c
> @@ -105,7 +105,7 @@ static ktime_t tick_init_jiffy_update(void)
> /*
> * NO HZ enabled ?
> */
> -static int tick_nohz_enabled __read_mostly = 1;
> +int tick_nohz_enabled __read_mostly = 1;
>
> /*
> * Enable / Disable tickless mode
>
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