On Tue, Jan 08, 2013 at 03:08:08AM +0100, Frederic Weisbecker wrote:
> This way the full nohz CPUs can safely run with the tick
> stopped with a guarantee that somebody else is taking
> care of the jiffies and gtod progression.
>
> NOTE: this doesn't handle CPU hotplug. Also we could use something
> more elaborated wrt. powersaving if we have more than one non full-nohz
> CPU running. But let's use this KISS solution for now.
>
> Signed-off-by: Frederic Weisbecker <fweis...@gmail.com>
> Cc: Alessio Igor Bogani <abog...@kernel.org>
> Cc: Andrew Morton <a...@linux-foundation.org>
> Cc: Chris Metcalf <cmetc...@tilera.com>
> Cc: Christoph Lameter <c...@linux.com>
> Cc: Geoff Levand <ge...@infradead.org>
> Cc: Gilad Ben Yossef <gi...@benyossef.com>
> Cc: Hakan Akkan <hakanak...@gmail.com>
> Cc: Ingo Molnar <mi...@kernel.org>
> Cc: Li Zhong <zh...@linux.vnet.ibm.com>
> Cc: Namhyung Kim <namhyung....@lge.com>
> Cc: Paul E. McKenney <paul...@linux.vnet.ibm.com>
> Cc: Paul Gortmaker <paul.gortma...@windriver.com>
> Cc: Peter Zijlstra <pet...@infradead.org>
> Cc: Steven Rostedt <rost...@goodmis.org>
> Cc: Thomas Gleixner <t...@linutronix.de>
> [fix have_nohz_full_mask offcase]
> Signed-off-by: Steven Rostedt <rost...@goodmis.org>
> ---
> kernel/time/tick-broadcast.c | 3 ++-
> kernel/time/tick-common.c | 5 ++++-
> kernel/time/tick-sched.c | 9 ++++++++-
> 3 files changed, 14 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
> index f113755..596c547 100644
> --- a/kernel/time/tick-broadcast.c
> +++ b/kernel/time/tick-broadcast.c
> @@ -537,7 +537,8 @@ void tick_broadcast_setup_oneshot(struct
> clock_event_device *bc)
> bc->event_handler = tick_handle_oneshot_broadcast;
>
> /* Take the do_timer update */
> - tick_do_timer_cpu = cpu;
> + if (!tick_nohz_full_cpu(cpu))
> + tick_do_timer_cpu = cpu;
>
> /*
> * We must be careful here. There might be other CPUs
> diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
> index b1600a6..83f2bd9 100644
> --- a/kernel/time/tick-common.c
> +++ b/kernel/time/tick-common.c
> @@ -163,7 +163,10 @@ static void tick_setup_device(struct tick_device *td,
> * this cpu:
> */
> if (tick_do_timer_cpu == TICK_DO_TIMER_BOOT) {
> - tick_do_timer_cpu = cpu;
> + if (!tick_nohz_full_cpu(cpu))
> + tick_do_timer_cpu = cpu;
> + else
> + tick_do_timer_cpu = TICK_DO_TIMER_NONE;
> tick_next_period = ktime_get();
> tick_period = ktime_set(0, NSEC_PER_SEC / HZ);
> }
> diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
> index 494a2aa..b75e302 100644
> --- a/kernel/time/tick-sched.c
> +++ b/kernel/time/tick-sched.c
> @@ -112,7 +112,8 @@ static void tick_sched_do_timer(ktime_t now)
> * this duty, then the jiffies update is still serialized by
> * jiffies_lock.
> */
> - if (unlikely(tick_do_timer_cpu == TICK_DO_TIMER_NONE))
> + if (unlikely(tick_do_timer_cpu == TICK_DO_TIMER_NONE)
> + && !tick_nohz_full_cpu(cpu))
> tick_do_timer_cpu = cpu;
> #endif
>
> @@ -163,6 +164,8 @@ static int __init tick_nohz_full_setup(char *str)
> return 1;
> }
> __setup("full_nohz=", tick_nohz_full_setup);
> +#else
> +#define have_full_nohz_mask (0)
> #endif
Looks like this hunk should be part of the previous patch, no?
...
Oui, oui monsieur! :-)
--
Regards/Gruss,
Boris.
Sent from a fat crate under my desk. Formatting is fine.
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