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From: Christoph Lameter <cl@gentwo.org>
To: Sasha Levin <sasha.levin@oracle.com>
Cc: Tejun Heo <tj@kernel.org>, Peter Zijlstra <peterz@infradead.org>,
	akpm@linux-foundation.org, Gilad Ben-Yossef <gilad@benyossef.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	John Stultz <johnstul@us.ibm.com>,
	Mike Frysinger <vapier@gentoo.org>,
	Minchan Kim <minchan.kim@gmail.com>,
	Hakan Akkan <hakanakkan@gmail.com>,
	Max Krasnyansky <maxk@qualcomm.com>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	hughd@google.com, viresh.kumar@linaro.org, hpa@zytor.com,
	mingo@kernel.org, Lai Jiangshan <laijs@cn.fujitsu.com>
Subject: Re: vmstat: On demand vmstat workers V8
Date: Tue, 29 Jul 2014 10:59:46 -0500 (CDT)	[thread overview]
Message-ID: <alpine.DEB.2.11.1407291057410.21390@gentwo.org> (raw)
In-Reply-To: <53D7C1F8.5040800@oracle.com>

On Tue, 29 Jul 2014, Sasha Levin wrote:

> > Index: linux/mm/vmstat.c
> > ===================================================================
> > --- linux.orig/mm/vmstat.c	2014-07-29 10:22:45.073884943 -0500
> > +++ linux/mm/vmstat.c	2014-07-29 10:34:45.083369228 -0500
> > @@ -1277,8 +1277,8 @@ static int vmstat_cpuup_callback(struct
> >  		break;
> >  	case CPU_DOWN_PREPARE:
> >  	case CPU_DOWN_PREPARE_FROZEN:
> > -		cancel_delayed_work_sync(&per_cpu(vmstat_work, cpu));
> >  		per_cpu(vmstat_work, cpu).work.func = NULL;
> > +		cancel_delayed_work_sync(&per_cpu(vmstat_work, cpu));
> >  		break;
> >  	case CPU_DOWN_FAILED:
> >  	case CPU_DOWN_FAILED_FROZEN:
> >
>
> I'm slightly confused here. The on demand vmstat workers patch did this:
>
>         case CPU_DOWN_PREPARE_FROZEN:
> -               cancel_delayed_work_sync(&per_cpu(vmstat_work, cpu));
> -               per_cpu(vmstat_work, cpu).work.func = NULL;
> +               if (!cpumask_test_and_set_cpu(cpu, cpu_stat_off))
> +                       cancel_delayed_work_sync(&per_cpu(vmstat_work, cpu));
>
> So your new patch doesn't apply on top of it, and doesn't make sense before it.

Tejun was looking at upsteram and so I fixed upstream ;-)

Is it really necessary to set the work.func to NULL? If so then the
work.func will have to be initialized when a processor is brought online.

Canceling the work should be enough to disable the execution of the
function.


WARNING: multiple messages have this Message-ID (diff)
From: Christoph Lameter <cl@gentwo.org>
To: Sasha Levin <sasha.levin@oracle.com>
Cc: Tejun Heo <tj@kernel.org>, Peter Zijlstra <peterz@infradead.org>,
	akpm@linux-foundation.org, Gilad Ben-Yossef <gilad@benyossef.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	John Stultz <johnstul@us.ibm.com>,
	Mike Frysinger <vapier@gentoo.org>,
	Minchan Kim <minchan.kim@gmail.com>,
	Hakan Akkan <hakanakkan@gmail.com>,
	Max Krasnyansky <maxk@qualcomm.com>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	hughd@google.com, viresh.kumar@linaro.org, hpa@zytor.com,
	mingo@kernel.org, Lai Jiangshan <laijs@cn.fujitsu.com>
Subject: Re: vmstat: On demand vmstat workers V8
Date: Tue, 29 Jul 2014 10:59:46 -0500 (CDT)	[thread overview]
Message-ID: <alpine.DEB.2.11.1407291057410.21390@gentwo.org> (raw)
In-Reply-To: <53D7C1F8.5040800@oracle.com>

On Tue, 29 Jul 2014, Sasha Levin wrote:

> > Index: linux/mm/vmstat.c
> > ===================================================================
> > --- linux.orig/mm/vmstat.c	2014-07-29 10:22:45.073884943 -0500
> > +++ linux/mm/vmstat.c	2014-07-29 10:34:45.083369228 -0500
> > @@ -1277,8 +1277,8 @@ static int vmstat_cpuup_callback(struct
> >  		break;
> >  	case CPU_DOWN_PREPARE:
> >  	case CPU_DOWN_PREPARE_FROZEN:
> > -		cancel_delayed_work_sync(&per_cpu(vmstat_work, cpu));
> >  		per_cpu(vmstat_work, cpu).work.func = NULL;
> > +		cancel_delayed_work_sync(&per_cpu(vmstat_work, cpu));
> >  		break;
> >  	case CPU_DOWN_FAILED:
> >  	case CPU_DOWN_FAILED_FROZEN:
> >
>
> I'm slightly confused here. The on demand vmstat workers patch did this:
>
>         case CPU_DOWN_PREPARE_FROZEN:
> -               cancel_delayed_work_sync(&per_cpu(vmstat_work, cpu));
> -               per_cpu(vmstat_work, cpu).work.func = NULL;
> +               if (!cpumask_test_and_set_cpu(cpu, cpu_stat_off))
> +                       cancel_delayed_work_sync(&per_cpu(vmstat_work, cpu));
>
> So your new patch doesn't apply on top of it, and doesn't make sense before it.

Tejun was looking at upsteram and so I fixed upstream ;-)

Is it really necessary to set the work.func to NULL? If so then the
work.func will have to be initialized when a processor is brought online.

Canceling the work should be enough to disable the execution of the
function.

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  reply	other threads:[~2014-07-29 15:59 UTC|newest]

Thread overview: 73+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-07-10 14:04 vmstat: On demand vmstat workers V8 Christoph Lameter
2014-07-10 14:04 ` Christoph Lameter
2014-07-11 13:20 ` Frederic Weisbecker
2014-07-11 13:20   ` Frederic Weisbecker
2014-07-11 13:56   ` Christoph Lameter
2014-07-11 13:56     ` Christoph Lameter
2014-07-11 13:58     ` Frederic Weisbecker
2014-07-11 13:58       ` Frederic Weisbecker
2014-07-11 15:17       ` Christoph Lameter
2014-07-11 15:17         ` Christoph Lameter
2014-07-11 15:19         ` Frederic Weisbecker
2014-07-11 15:19           ` Frederic Weisbecker
2014-07-11 15:22           ` Christoph Lameter
2014-07-11 15:22             ` Christoph Lameter
2014-07-14 20:10             ` Hugh Dickins
2014-07-14 20:10               ` Hugh Dickins
2014-07-14 20:51               ` Christoph Lameter
2014-07-14 20:51                 ` Christoph Lameter
2014-07-30  3:04         ` Lai Jiangshan
2014-07-30  3:04           ` Lai Jiangshan
2014-07-26  2:22 ` Sasha Levin
2014-07-26  2:22   ` Sasha Levin
2014-07-28 18:55   ` Christoph Lameter
2014-07-28 18:55     ` Christoph Lameter
2014-07-28 21:54     ` Andrew Morton
2014-07-28 21:54       ` Andrew Morton
2014-07-28 22:00       ` Sasha Levin
2014-07-28 22:00         ` Sasha Levin
2014-07-29 15:17       ` Christoph Lameter
2014-07-29 15:17         ` Christoph Lameter
2014-07-29  7:56     ` Peter Zijlstra
2014-07-29 12:05       ` Tejun Heo
2014-07-29 12:05         ` Tejun Heo
2014-07-29 12:23         ` Peter Zijlstra
2014-07-29 12:23           ` Peter Zijlstra
2014-07-29 13:12           ` Tejun Heo
2014-07-29 13:12             ` Tejun Heo
2014-07-29 15:10             ` Christoph Lameter
2014-07-29 15:10               ` Christoph Lameter
2014-07-29 15:14               ` Tejun Heo
2014-07-29 15:14                 ` Tejun Heo
2014-07-29 15:26                 ` Christoph Lameter
2014-07-29 15:26                   ` Christoph Lameter
2014-07-29 15:39                 ` Christoph Lameter
2014-07-29 15:39                   ` Christoph Lameter
2014-07-29 15:47                   ` Sasha Levin
2014-07-29 15:47                     ` Sasha Levin
2014-07-29 15:59                     ` Christoph Lameter [this message]
2014-07-29 15:59                       ` Christoph Lameter
2014-07-30  3:11                   ` Lai Jiangshan
2014-07-30  3:11                     ` Lai Jiangshan
2014-07-30 14:34                     ` Christoph Lameter
2014-07-30 14:34                       ` Christoph Lameter
2014-07-29 15:22             ` Christoph Lameter
2014-07-29 15:22               ` Christoph Lameter
2014-07-29 15:43               ` Sasha Levin
2014-07-29 15:43                 ` Sasha Levin
2014-08-04 21:37   ` Sasha Levin
2014-08-04 21:37     ` Sasha Levin
2014-08-05 14:51     ` Christoph Lameter
2014-08-05 14:51       ` Christoph Lameter
2014-08-05 22:25       ` Sasha Levin
2014-08-05 22:25         ` Sasha Levin
2014-08-06 14:12         ` Christoph Lameter
2014-08-06 14:12           ` Christoph Lameter
2014-08-07  1:50           ` Sasha Levin
2014-08-07  1:50             ` Sasha Levin
2014-07-30  2:57 ` Lai Jiangshan
2014-07-30  2:57   ` Lai Jiangshan
2014-07-30 14:45   ` Christoph Lameter
2014-07-30 14:45     ` Christoph Lameter
2014-07-31  0:52     ` Lai Jiangshan
2014-07-31  0:52       ` Lai Jiangshan

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