diff options
| author | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2009-09-29 14:25:16 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2010-08-13 13:20:13 -0700 |
| commit | 7bfa0a73b2723bf4cc8a154534c351f31f8a120f (patch) | |
| tree | b46aca4fc4472116bba2de6410b21010f874f664 /include | |
| parent | 55f32f8ac693e2bb4081d7cec1144b0250182267 (diff) | |
nohz: Introduce arch_needs_cpu
commit 3c5d92a0cfb5103c0d5ab74d4ae6373d3af38148 upstream.
Allow the architecture to request a normal jiffy tick when the system
goes idle and tick_nohz_stop_sched_tick is called . On s390 the hook is
used to prevent the system going fully idle if there has been an
interrupt other than a clock comparator interrupt since the last wakeup.
On s390 the HiperSockets response time for 1 connection ping-pong goes
down from 42 to 34 microseconds. The CPU cost decreases by 27%.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
LKML-Reference: <20090929122533.402715150@de.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Jolly <jjolly@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/tick.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/include/linux/tick.h b/include/linux/tick.h index 0482229c07db..8dc082194b22 100644 --- a/include/linux/tick.h +++ b/include/linux/tick.h @@ -98,6 +98,9 @@ extern int tick_check_oneshot_change(int allow_nohz); extern struct tick_sched *tick_get_tick_sched(int cpu); extern void tick_check_idle(int cpu); extern int tick_oneshot_mode_active(void); +# ifndef arch_needs_cpu +# define arch_needs_cpu(cpu) (0) +# endif # else static inline void tick_clock_notify(void) { } static inline int tick_check_oneshot_change(int allow_nohz) { return 0; } |