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 --- arch/s390/kernel/s390_ext.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'arch/s390/kernel/s390_ext.c') diff --git a/arch/s390/kernel/s390_ext.c b/arch/s390/kernel/s390_ext.c index 0de305b598c..59618bcd99b 100644 --- a/arch/s390/kernel/s390_ext.c +++ b/arch/s390/kernel/s390_ext.c @@ -126,6 +126,8 @@ void __irq_entry do_extint(struct pt_regs *regs, unsigned short code) /* Serve timer interrupts first. */ clock_comparator_work(); kstat_cpu(smp_processor_id()).irqs[EXTERNAL_INTERRUPT]++; + if (code != 0x1004) + __get_cpu_var(s390_idle).nohz_delay = 1; index = ext_hash(code); for (p = ext_int_hash[index]; p; p = p->next) { if (likely(p->code == code)) -- cgit v1.2.3