2013/2/15 Borislav Petkov <b...@alien8.de>:
> 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?
Ah probably yeah :)
> Oui, oui monsieur! :-)
:)
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