[tip:timers/core] clockevents: Remove the per cpu tick skew
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From: tip-bot for Arjan van de Ven on 2 Aug 2010 15:50 Commit-ID: af5ab277ded04bd9bc6b048c5a2f0e7d70ef0867 Gitweb: http://git.kernel.org/tip/af5ab277ded04bd9bc6b048c5a2f0e7d70ef0867 Author: Arjan van de Ven <arjan(a)infradead.org> AuthorDate: Tue, 27 Jul 2010 21:02:10 -0700 Committer: Thomas Gleixner <tglx(a)linutronix.de> CommitDate: Mon, 2 Aug 2010 21:45:58 +0200 clockevents: Remove the per cpu tick skew Historically, Linux has tried to make the regular timer tick on the various CPUs not happen at the same time, to avoid contention on xtime_lock. Nowadays, with the tickless kernel, this contention no longer happens since time keeping and updating are done differently. In addition, this skew is actually hurting power consumption in a measurable way on many-core systems. Signed-off-by: Arjan van de Ven <arjan(a)linux.intel.com> LKML-Reference: <20100727210210.58d3118c(a)infradead.org> Signed-off-by: Thomas Gleixner <tglx(a)linutronix.de> --- kernel/time/tick-sched.c | 5 ----- 1 files changed, 0 insertions(+), 5 deletions(-) diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 813993b..74644cc 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -780,7 +780,6 @@ void tick_setup_sched_timer(void) { struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched); ktime_t now = ktime_get(); - u64 offset; /* * Emulate tick processing via per-CPU hrtimers: @@ -790,10 +789,6 @@ void tick_setup_sched_timer(void) /* Get the next period (per cpu) */ hrtimer_set_expires(&ts->sched_timer, tick_init_jiffy_update()); - offset = ktime_to_ns(tick_period) >> 1; - do_div(offset, num_possible_cpus()); - offset *= smp_processor_id(); - hrtimer_add_expires_ns(&ts->sched_timer, offset); for (;;) { hrtimer_forward(&ts->sched_timer, now, tick_period); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |