From: Heiko Carstens <heiko.carstens@de.ibm.com>
To: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: linux-kernel@vger.kernel.org, rt@linutronix.de,
Martin Schwidefsky <schwidefsky@de.ibm.com>,
linux-s390@vger.kernel.org
Subject: Re: [PATCH] s390/cpum_sf: Remove superfluous SMP function call
Date: Tue, 5 Apr 2016 12:49:12 +0200 [thread overview]
Message-ID: <20160405104912.GC3937@osiris> (raw)
In-Reply-To: <1459765640-13599-1-git-send-email-anna-maria@linutronix.de>
On Mon, Apr 04, 2016 at 12:27:20PM +0200, Anna-Maria Gleixner wrote:
> Since commit 1cf4f629d9d2 ("cpu/hotplug: Move online calls to
> hotplugged cpu") it is ensured that callbacks of CPU_ONLINE and
> CPU_DOWN_PREPARE are processed on the hotplugged CPU. Due to this SMP
> function calls are no longer required.
>
> Replace smp_call_function_single() with a direct call of
> setup_pmc_cpu(). To keep the calling convention, interrupts are
> explicitely disabled around the call.
>
> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
> Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
> Cc: linux-s390@vger.kernel.org
> Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
> ---
> arch/s390/kernel/perf_cpum_sf.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
>
> --- a/arch/s390/kernel/perf_cpum_sf.c
> +++ b/arch/s390/kernel/perf_cpum_sf.c
> @@ -1510,7 +1510,6 @@ static void cpumf_measurement_alert(stru
> static int cpumf_pmu_notifier(struct notifier_block *self,
> unsigned long action, void *hcpu)
> {
> - unsigned int cpu = (long) hcpu;
> int flags;
>
> /* Ignore the notification if no events are scheduled on the PMU.
> @@ -1523,11 +1522,15 @@ static int cpumf_pmu_notifier(struct not
> case CPU_ONLINE:
> case CPU_DOWN_FAILED:
> flags = PMC_INIT;
> - smp_call_function_single(cpu, setup_pmc_cpu, &flags, 1);
> + local_irq_disable();
> + setup_pmc_cpu(&flags);
> + local_irq_enable();
> break;
...but at least the CPU_DOWN_FAILED callback will not necessarily be called
on the cpu that couldn't be brought offline.
next prev parent reply other threads:[~2016-04-05 10:49 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-04 10:27 [PATCH] s390/cpum_sf: Remove superfluous SMP function call Anna-Maria Gleixner
2016-04-05 10:49 ` Heiko Carstens [this message]
2016-04-05 11:13 ` [PREEMPT-RT] " Sebastian Andrzej Siewior
2016-04-05 11:23 ` Heiko Carstens
2016-04-05 11:36 ` Heiko Carstens
2016-04-05 11:51 ` rcochran
2016-04-05 11:55 ` Heiko Carstens
2016-04-05 11:57 ` Sebastian Andrzej Siewior
2016-04-05 12:11 ` Heiko Carstens
2016-04-05 12:19 ` Sebastian Andrzej Siewior
2016-04-05 15:59 ` [PATCH] cpu/hotplug: fix rollback during error-out in __cpu_disable() Sebastian Andrzej Siewior
2016-04-06 19:51 ` Heiko Carstens
2016-04-07 15:14 ` Sebastian Andrzej Siewior
2016-04-08 6:19 ` Heiko Carstens
2016-04-08 12:40 ` [PATCH v2] " Sebastian Andrzej Siewior
2016-04-22 7:54 ` [tip:smp/urgent] cpu/hotplug: Fix " tip-bot for Sebastian Andrzej Siewior
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