From 3c5d92a0cfb5103c0d5ab74d4ae6373d3af38148 Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Tue, 29 Sep 2009 14:25:16 +0200 Subject: nohz: Introduce arch_needs_cpu 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 LKML-Reference: <20090929122533.402715150@de.ibm.com> Signed-off-by: Thomas Gleixner --- include/linux/tick.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include/linux/tick.h') 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; } -- cgit v1.2.3-55-g7522