On Tue, 2014-06-24 at 12:02 +0800, Rui Xiang wrote:
> Hi Greg or Thomas,
>
> 0e576acbc1d9600cf2d9b4a141a2554639959d50
> nohz: Fix another inconsistency between CONFIG_NO_HZ=n and nohz=off
>
> This fixed an inconsistency about nohz.
>
> Without this patch, When we boot with nohz=off and CONFIG_NO_HZ=Y,
> and the system is idle, powertop shows the cpu is always in polling
> state. It can affect the performance in some cases.
[...]
> This patch looks applicable to stable-3.4 and stable 3.10. It can be
> applyed to 3.10 cleanly, but should be added some adjustment for 3.4.
>
> And what do you think?
I've queued this up for 3.2, with adjusted context:
[...]
> --- a/kernel/time/tick-sched.c
> +++ b/kernel/time/tick-sched.c
> @@ -296,8 +296,10 @@ static void tick_nohz_stop_sched_tick(struct tick_sched *ts)
> tick_do_timer_cpu = TICK_DO_TIMER_NONE;
> }
>
> - if (unlikely(ts->nohz_mode == NOHZ_MODE_INACTIVE))
> + if (unlikely(ts->nohz_mode == NOHZ_MODE_INACTIVE)) {
> + ts->sleep_length = (ktime_t) { .tv64 = NSEC_PER_SEC/HZ };
> return;
Here there is a 'goto end' rather than 'return'.
> + }
>
> if (need_resched())
> return;
And here too.
Ben.
--
Ben Hutchings
Kids! Bringing about Armageddon can be dangerous. Do not attempt it in
your own home. - Terry Pratchett and Neil Gaiman, `Good Omens'
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