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authorFrederic Weisbecker <fweisbec@gmail.com>2012-12-18 18:24:35 +0100
committerFrederic Weisbecker <fweisbec@gmail.com>2013-03-21 15:55:45 +0100
commita382bf934449ddeb625167537ae81daa0211b477 (patch)
tree6ee5becb6b01c952d8fb7d561e10c1e2967d7b99 /kernel/time/tick-common.c
parenta831881be220358a1d28c5d95d69449fb6d623ca (diff)
downloadop-kernel-dev-a382bf934449ddeb625167537ae81daa0211b477.zip
op-kernel-dev-a382bf934449ddeb625167537ae81daa0211b477.tar.gz
nohz: Assign timekeeping duty to a CPU outside the full dynticks range
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. Once the duty is attributed to a CPU, it won't change. Also that CPU can't enter into dyntick idle mode or be hot unplugged. This may later be improved from a power consumption POV. At least we should be able to share the duty amongst all CPUs outside the full dynticks range. Then the duty could even be shared with full dynticks CPUs when those can't stop their tick for any reason. But let's start with that very simple approach first. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Christoph Lameter <cl@linux.com> Cc: Geoff Levand <geoff@infradead.org> Cc: Gilad Ben Yossef <gilad@benyossef.com> Cc: Hakan Akkan <hakanakkan@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kevin Hilman <khilman@linaro.org> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Namhyung Kim <namhyung.kim@lge.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> [fix have_nohz_full_mask offcase] Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'kernel/time/tick-common.c')
-rw-r--r--kernel/time/tick-common.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
index b1600a6..b7dc0cb 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_extended_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);
}
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