linux-kernel - Re: current linux-2.6.git: cpusets completely broken

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Message-ID: <4877EA9A.1070700@qualcomm.com>
Date:	Fri, 11 Jul 2008 16:19:54 -0700
From:	Max Krasnyansky <maxk@...lcomm.com>
To:	Dmitry Adamushko <dmitry.adamushko@...il.com>
CC:	Vegard Nossum <vegard.nossum@...il.com>,
	Paul Menage <menage@...gle.com>, Paul Jackson <pj@....com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>, miaox@...fujitsu.com,
	rostedt@...dmis.org, Thomas Gleixner <tglx@...utronix.de>,
	Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: current linux-2.6.git: cpusets completely broken

Dmitry Adamushko wrote:
> Does the patch below help?
> 
> (non-white-space-damaged version is attached)
> 
> diff --git a/kernel/cpuset.c b/kernel/cpuset.c
> index 9fceb97..ae61dc9 100644
> --- a/kernel/cpuset.c
> +++ b/kernel/cpuset.c
> @@ -1912,11 +1912,21 @@ static void common_cpu_mem_hotplug_unplug(void)
>  static int cpuset_handle_cpuhp(struct notifier_block *unused_nb,
>                                 unsigned long phase, void *unused_cpu)
>  {
> -       if (phase == CPU_DYING || phase == CPU_DYING_FROZEN)
> +       swicth (phase) {
> +       case CPU_UP_CANCELED:
> +       case CPU_UP_CANCELED_FROZEN:
> +       case CPU_DOWN_FAILED:
> +       case CPU_DOWN_FAILED_FROZEN:
> +       case CPU_ONLINE:
> +       case CPU_ONLINE_FROZEN:
> +       case CPU_DEAD:
> +       case CPU_DEAD_FROZEN:
> +               common_cpu_mem_hotplug_unplug();
> +               break;
> +       default:
>                 return NOTIFY_DONE;

I was always wondering why we're running that logic for every hotplug 
event.
For example, do we care for UP_CANCELED* and DOWN_FAILED* ? Presumably 
nothing should've changed, no ?
btw I'm just going by the name of the event. So UP_CANCELED to me sounds 
like CPU never got to the ONLINE stage and cpuset should not really care.

Max


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