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| author | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2009-09-29 14:25:16 +0200 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2009-11-05 07:53:53 +0100 |
| commit | 3c5d92a0cfb5103c0d5ab74d4ae6373d3af38148 (patch) | |
| tree | c8b50351568601428b6f9396ebfdd65e486b3097 /drivers/s390/cio | |
| parent | eed3b9cf3fe3fcc7a50238dfcab63a63914e8f42 (diff) | |
| download | linux-3c5d92a0cfb5103c0d5ab74d4ae6373d3af38148.tar.bz2 | |
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')
| -rw-r--r-- | drivers/s390/cio/cio.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/s390/cio/cio.c b/drivers/s390/cio/cio.c index 138124fcfcad..126f240715a4 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(); |