Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933745Ab3CHEi0 (ORCPT ); Thu, 7 Mar 2013 23:38:26 -0500 Received: from mail-pb0-f53.google.com ([209.85.160.53]:56204 "EHLO mail-pb0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760392Ab3CHEiY (ORCPT ); Thu, 7 Mar 2013 23:38:24 -0500 Message-ID: <51396B39.3090504@linaro.org> Date: Fri, 08 Mar 2013 05:38:17 +0100 From: Daniel Lezcano User-Agent: Mozilla/5.0 (X11; Linux i686; rv:17.0) Gecko/20130106 Thunderbird/17.0.2 MIME-Version: 1.0 To: Thomas Gleixner CC: john.stultz@linaro.org, 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: Re: [PATCH 2/4][V2] time : set broadcast irq affinity References: <1362219013-18173-1-git-send-email-daniel.lezcano@linaro.org> <1362219013-18173-3-git-send-email-daniel.lezcano@linaro.org> <51370C09.5020301@linaro.org> In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3877 Lines: 101 On 03/06/2013 10:48 AM, Thomas Gleixner wrote: > On Wed, 6 Mar 2013, Daniel Lezcano wrote: >> On 03/05/2013 09:40 PM, Thomas Gleixner wrote: >>> On Sat, 2 Mar 2013, Daniel Lezcano wrote: >>>> 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; >>> >>> This breaks with CONFIG_CPUMASK_OFFSTACK=y. cpumask_copy() is your friend! >> >> This instruction copies the pointer, not the cpumask content. >> >> bc->cpumask is defined as a const struct cpumask * and is used to copy a >> cpumask pointer not the content. >> >> The cpumask parameter is a pointer to a global cpumask provided by the >> cpumask_of macro. >> >> But to be in the safe side, I compiled tested with >> CONFIG_CPUMASK_OFFSTACK=y without problem. Hi Thomas, thanks for merging the patch 1 and 2. I was wondering if it would be possible to take the 3/4 and 4/4 otherwise the flag dependency will prevent to send those to the maintainer's tree until they gain visibility on it. -- Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog -- 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/