Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752188Ab3CBKKX (ORCPT ); Sat, 2 Mar 2013 05:10:23 -0500 Received: from mail-we0-f181.google.com ([74.125.82.181]:48372 "EHLO mail-we0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751998Ab3CBKKR (ORCPT ); Sat, 2 Mar 2013 05:10:17 -0500 From: Daniel Lezcano To: john.stultz@linaro.org, tglx@linutronix.de Cc: viresh.kumar@linaro.org, jacob.jun.pan@linux.intel.com, linux-arm-kernel@lists.infradead.org, santosh.shilimkar@ti.com, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, linaro-kernel@lists.linaro.org, patches@linaro.org, rickard.andersson@stericsson.com, vincent.guittot@linaro.org, linus.walleij@stericsson.com Subject: [PATCH 2/4][V2] time : set broadcast irq affinity Date: Sat, 2 Mar 2013 11:10:11 +0100 Message-Id: <1362219013-18173-3-git-send-email-daniel.lezcano@linaro.org> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1362219013-18173-1-git-send-email-daniel.lezcano@linaro.org> References: <1362219013-18173-1-git-send-email-daniel.lezcano@linaro.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4752 Lines: 139 When a cpu goes to a deep idle state where its local timer is shutdown, it notifies the time frame work to use the broadcast timer instead. Unfortunately, the broadcast device could wake up any CPU, including an idle one which is not concerned by the wake up at all. This implies, in the worst case, an idle CPU will wake up to send an IPI to another idle cpu. This patch solves this by setting the irq affinity to the cpu concerned by the nearest timer event, by this way, the CPU which is wake up is guarantee to be the one concerned by the next event and we are safe with unnecessary wakeup for another idle CPU. As the irq affinity is not supported by all the archs, a flag is needed to specify which clocksource can handle it : CLOCK_EVT_FEAT_DYNIRQ Signed-off-by: Daniel Lezcano --- include/linux/clockchips.h | 5 +++++ kernel/time/tick-broadcast.c | 40 +++++++++++++++++++++++++++++++++------- 2 files changed, 38 insertions(+), 7 deletions(-) diff --git a/include/linux/clockchips.h b/include/linux/clockchips.h index 6634652..c93e2a6 100644 --- a/include/linux/clockchips.h +++ b/include/linux/clockchips.h @@ -55,6 +55,11 @@ enum clock_event_nofitiers { #define CLOCK_EVT_FEAT_C3STOP 0x000008 #define CLOCK_EVT_FEAT_DUMMY 0x000010 +/* + * Clock event device can set its irq affinity dynamically + */ +#define CLOCK_EVT_FEAT_DYNIRQ 0x000020 + /** * struct clock_event_device - clock event device descriptor * @event_handler: Assigned by the framework to be called by the low diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c index 6197ac0..9ca8ff5 100644 --- a/kernel/time/tick-broadcast.c +++ b/kernel/time/tick-broadcast.c @@ -406,13 +406,37 @@ struct cpumask *tick_get_broadcast_oneshot_mask(void) return to_cpumask(tick_broadcast_oneshot_mask); } -static int tick_broadcast_set_event(struct clock_event_device *bc, +/* + * Set broadcast interrupt affinity + */ +static void tick_broadcast_set_affinity(struct clock_event_device *bc, + const struct cpumask *cpumask) +{ + if (!(bc->features & CLOCK_EVT_FEAT_DYNIRQ)) + return; + + if (cpumask_equal(bc->cpumask, cpumask)) + return; + + bc->cpumask = cpumask; + irq_set_affinity(bc->irq, bc->cpumask); +} + +static int tick_broadcast_set_event(struct clock_event_device *bc, int cpu, ktime_t expires, int force) { + int ret; + if (bc->mode != CLOCK_EVT_MODE_ONESHOT) clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT); - return clockevents_program_event(bc, expires, force); + ret = clockevents_program_event(bc, expires, force); + if (ret) + return ret; + + tick_broadcast_set_affinity(bc, cpumask_of(cpu)); + + return 0; } int tick_resume_broadcast_oneshot(struct clock_event_device *bc) @@ -441,7 +465,7 @@ static void tick_handle_oneshot_broadcast(struct clock_event_device *dev) { struct tick_device *td; ktime_t now, next_event; - int cpu; + int cpu, next_cpu; raw_spin_lock(&tick_broadcast_lock); again: @@ -454,8 +478,10 @@ again: td = &per_cpu(tick_cpu_device, cpu); if (td->evtdev->next_event.tv64 <= now.tv64) cpumask_set_cpu(cpu, to_cpumask(tmpmask)); - else if (td->evtdev->next_event.tv64 < next_event.tv64) + else if (td->evtdev->next_event.tv64 < next_event.tv64) { next_event.tv64 = td->evtdev->next_event.tv64; + next_cpu = cpu; + } } /* @@ -478,7 +504,7 @@ again: * Rearm the broadcast device. If event expired, * repeat the above */ - if (tick_broadcast_set_event(dev, next_event, 0)) + if (tick_broadcast_set_event(dev, next_cpu, next_event, 0)) goto again; } raw_spin_unlock(&tick_broadcast_lock); @@ -521,7 +547,7 @@ void tick_broadcast_oneshot_control(unsigned long reason) cpumask_set_cpu(cpu, tick_get_broadcast_oneshot_mask()); clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN); if (dev->next_event.tv64 < bc->next_event.tv64) - tick_broadcast_set_event(bc, dev->next_event, 1); + tick_broadcast_set_event(bc, cpu, dev->next_event, 1); } } else { if (cpumask_test_cpu(cpu, tick_get_broadcast_oneshot_mask())) { @@ -590,7 +616,7 @@ void tick_broadcast_setup_oneshot(struct clock_event_device *bc) clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT); tick_broadcast_init_next_event(to_cpumask(tmpmask), tick_next_period); - tick_broadcast_set_event(bc, tick_next_period, 1); + tick_broadcast_set_event(bc, cpu, tick_next_period, 1); } else bc->next_event.tv64 = KTIME_MAX; } else { -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/