linux-kernel - Re: [RFC] Patch: dynticks: idle load balancing

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Message-ID: <20061219131223.E23105@unix-os.sc.intel.com>
Date:	Tue, 19 Dec 2006 13:12:24 -0800
From:	"Siddha, Suresh B" <suresh.b.siddha@...el.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	"Siddha, Suresh B" <suresh.b.siddha@...el.com>, vatsa@...ibm.com,
	clameter@....com, tglx@...utronix.de, arjan@...ux.intel.com,
	linux-kernel@...r.kernel.org
Subject: Re: [RFC] Patch: dynticks: idle load balancing

On Tue, Dec 19, 2006 at 09:12:48PM +0100, Ingo Molnar wrote:
>  restart:
>  	if (idle_cpu(local_cpu) && notick.load_balancer == local_cpu) {
>  		this_cpu = first_cpu(cpus);
> +		if (unlikely(this_cpu >= NR_CPUS))
> +			return;

oops.

There is window when local_cpu is cleared from notick.cpumask
but the notick.load_balancer still points to local_cpu..
This can also be corrected by first resetting the notick.load_balancer
before clearing that cpu from notick.cpumask in select_notick_load_balancer()

thanks,
suresh
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