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authorMartin Schwidefsky <schwidefsky@de.ibm.com>2009-09-29 14:25:16 +0200
committerThomas Gleixner <tglx@linutronix.de>2009-11-05 07:53:53 +0100
commit3c5d92a0cfb5103c0d5ab74d4ae6373d3af38148 (patch)
treec8b50351568601428b6f9396ebfdd65e486b3097 /drivers/s390/cio/cio.c
parenteed3b9cf3fe3fcc7a50238dfcab63a63914e8f42 (diff)
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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 <schwidefsky@de.ibm.com> LKML-Reference: <20090929122533.402715150@de.ibm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'drivers/s390/cio/cio.c')
-rw-r--r--drivers/s390/cio/cio.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/s390/cio/cio.c b/drivers/s390/cio/cio.c
index 138124f..126f240 100644
--- a/drivers/s390/cio/cio.c
+++ b/drivers/s390/cio/cio.c
@@ -618,6 +618,7 @@ void __irq_entry do_IRQ(struct pt_regs *regs)
old_regs = set_irq_regs(regs);
s390_idle_check();
irq_enter();
+ __get_cpu_var(s390_idle).nohz_delay = 1;
if (S390_lowcore.int_clock >= S390_lowcore.clock_comparator)
/* Serve timer interrupts first. */
clock_comparator_work();
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