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Subject[tip:timers/urgent] hrtimers: Notify hrtimer users of switches to NOHZ mode
Commit-ID:  2d0640b47da74cff7c11642c798d40de861ed524
Gitweb: http://git.kernel.org/tip/2d0640b47da74cff7c11642c798d40de861ed524
Author: Stephen Boyd <sboyd@codeaurora.org>
AuthorDate: Tue, 18 Jan 2011 22:46:34 -0800
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Wed, 19 Jan 2011 20:08:15 +0100

hrtimers: Notify hrtimer users of switches to NOHZ mode

When NOHZ=y and high res timers are disabled (via cmdline or
Kconfig) tick_nohz_switch_to_nohz() will notify the user about
switching into NOHZ mode. Nothing is printed for the case where
HIGH_RES_TIMERS=y. Fix this for the HIGH_RES_TIMERS=y case by
duplicating the printk from the low res NOHZ path in the high
res NOHZ path.

This confused me since I was thinking 'dmesg | grep -i NOHZ' would
tell me if NOHZ was enabled, but if I have hrtimers there is
nothing.

Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1295419594-13085-1-git-send-email-sboyd@codeaurora.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
kernel/time/tick-sched.c | 7 ++++---
1 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 3e216e0..c55ea24 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -642,8 +642,7 @@ static void tick_nohz_switch_to_nohz(void)
}
local_irq_enable();

- printk(KERN_INFO "Switched to NOHz mode on CPU #%d\n",
- smp_processor_id());
+ printk(KERN_INFO "Switched to NOHz mode on CPU #%d\n", smp_processor_id());
}

/*
@@ -795,8 +794,10 @@ void tick_setup_sched_timer(void)
}

#ifdef CONFIG_NO_HZ
- if (tick_nohz_enabled)
+ if (tick_nohz_enabled) {
ts->nohz_mode = NOHZ_MODE_HIGHRES;
+ printk(KERN_INFO "Switched to NOHz mode on CPU #%d\n", smp_processor_id());
+ }
#endif
}
#endif /* HIGH_RES_TIMERS */

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