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authorThomas Gleixner <tglx@linutronix.de>2007-05-08 00:30:03 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-05-08 11:15:10 -0700
commitd3ed782458f315c30ea679b919a2cc59f2b82565 (patch)
treeb87fffc87acf5632566a6384f5c8be8f5c2e03b2 /kernel/time/tick-internal.h
parentd5d3b736e3264934ec832a657a9a434b65f3d51f (diff)
downloadlinaro-lsk-d3ed782458f315c30ea679b919a2cc59f2b82565.tar.gz
highres/dyntick: prevent xtime lock contention
While the !highres/!dyntick code assigns the duty of the do_timer() call to one specific CPU, this was dropped in the highres/dyntick part during development. Steven Rostedt discovered the xtime lock contention on highres/dyntick due to several CPUs trying to update jiffies. Add the single CPU assignement back. In the dyntick case this needs to be handled carefully, as the CPU which has the do_timer() duty must drop the assignement and let it be grabbed by another CPU, which is active. Otherwise the do_timer() calls would not happen during the long sleep. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Steven Rostedt <rostedt@goodmis.org> Acked-by: Mark Lord <mlord@pobox.com> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/time/tick-internal.h')
-rw-r--r--kernel/time/tick-internal.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/kernel/time/tick-internal.h b/kernel/time/tick-internal.h
index c9d203bde51..bb13f272490 100644
--- a/kernel/time/tick-internal.h
+++ b/kernel/time/tick-internal.h
@@ -5,6 +5,7 @@ DECLARE_PER_CPU(struct tick_device, tick_cpu_device);
extern spinlock_t tick_device_lock;
extern ktime_t tick_next_period;
extern ktime_t tick_period;
+extern int tick_do_timer_cpu __read_mostly;
extern void tick_setup_periodic(struct clock_event_device *dev, int broadcast);
extern void tick_handle_periodic(struct clock_event_device *dev);