linux-kernel - Re: [RFC PATCH] sched: find the latest idle cpu

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Date:	Wed, 15 Jan 2014 12:31:13 +0800
From:	Michael wang <wangyun@...ux.vnet.ibm.com>
To:	Alex Shi <alex.shi@...aro.org>, mingo@...hat.com,
	peterz@...radead.org, tglx@...utronix.de,
	daniel.lezcano@...aro.org, vincent.guittot@...aro.org,
	morten.rasmussen@....com
CC:	linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
	fengguang.wu@...el.com, linaro-kernel@...ts.linaro.org
Subject: Re: [RFC PATCH] sched: find the latest idle cpu

Hi, Alex

On 01/15/2014 12:07 PM, Alex Shi wrote:
[snip] 		}
> +#ifdef CONFIG_NO_HZ_COMMON
> +		/*
> +		 * Coarsely to get the latest idle cpu for shorter latency and
> +		 * possible power benefit.
> +		 */
> +		if (!min_load) {
> +			struct tick_sched *ts = &per_cpu(tick_cpu_sched, i);
> +
> +			s64 latest_wake = 0;

I guess we missed some code for latest_wake here?

Regards,
Michael Wang

> +			/* idle cpu doing irq */
> +			if (ts->inidle && !ts->idle_active)
> +				idlest = i;
> +			/* the cpu resched */
> +			else if (!ts->inidle)
> +				idlest = i;
> +			/* find latest idle cpu */
> +			else if (ktime_to_us(ts->idle_entrytime) > latest_wake)
> +				idlest = i;
> +		}
> +#endif
>  	}
> 
>  	return idlest;
> 

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