linux-kernel - Re: BUG: sched_mc_powersavings broken on pre-Nehalem x86 platforms

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Date:	Mon, 08 Feb 2010 12:35:48 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	svaidy@...ux.vnet.ibm.com
Cc:	Suresh B Siddha <suresh.b.siddha@...el.com>,
	Venkatesh Pallipadi <venkatesh.pallipadi@...el.com>,
	Ingo Molnar <mingo@...e.hu>, Gautham R Shenoy <ego@...ibm.com>,
	Arun Bharadwaj <arun@...ux.vnet.ibm.com>,
	Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: BUG: sched_mc_powersavings broken on pre-Nehalem x86 platforms

On Mon, 2010-02-08 at 15:35 +0530, Vaidyanathan Srinivasan wrote:

>     Fix for sched_mc_powersavigs for pre-Nehalem platforms.
>     Child sched domain should clear SD_PREFER_SIBLING if parent will have 
>     SD_POWERSAVINGS_BALANCE because they are contradicting.
> 
>     Sets the flags correctly based on sched_mc_power_savings.
>     
>     Signed-off-by: Vaidyanathan Srinivasan <svaidy@...ux.vnet.ibm.com>
> 
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index 6550415..ef6b7cd 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -866,7 +866,10 @@ static inline int sd_balance_for_mc_power(void)
>  	if (sched_smt_power_savings)
>  		return SD_POWERSAVINGS_BALANCE;
>  
> -	return SD_PREFER_SIBLING;
> +	if (!sched_mc_power_savings)
> +		return SD_PREFER_SIBLING;
> +
> +	return 0;
>  }
>  
>  static inline int sd_balance_for_package_power(void)
> 

Looks good, thanks!

What's the status of getting rid of sched_{mc,smt}_power_savings?

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