linux-kernel - Re: [patch v5 11/15] sched: add power/performance balance allow flag

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Date:	Wed, 20 Feb 2013 20:04:58 +0800
From:	Alex Shi <alex.shi@...el.com>
To:	Peter Zijlstra <peterz@...radead.org>
CC:	torvalds@...ux-foundation.org, mingo@...hat.com,
	tglx@...utronix.de, akpm@...ux-foundation.org,
	arjan@...ux.intel.com, bp@...en8.de, pjt@...gle.com,
	namhyung@...nel.org, efault@....de, vincent.guittot@...aro.org,
	gregkh@...uxfoundation.org, preeti@...ux.vnet.ibm.com,
	viresh.kumar@...aro.org, linux-kernel@...r.kernel.org,
	morten.rasmussen@....com
Subject: Re: [patch v5 11/15] sched: add power/performance balance allow flag

On 02/20/2013 05:48 PM, Peter Zijlstra wrote:
> On Mon, 2013-02-18 at 13:07 +0800, Alex Shi wrote:
>> @@ -4053,6 +4053,8 @@ struct lb_env {
>>         unsigned int            loop;
>>         unsigned int            loop_break;
>>         unsigned int            loop_max;
>> +       int                     power_lb;  /* if power balance needed
>> */
>> +       int                     perf_lb;   /* if performance balance
>> needed */
>>  };
>>  
>>  /*
>> @@ -5195,6 +5197,8 @@ static int load_balance(int this_cpu, struct rq
>> *this_rq,
>>                 .idle           = idle,
>>                 .loop_break     = sched_nr_migrate_break,
>>                 .cpus           = cpus,
>> +               .power_lb       = 0,
>> +               .perf_lb        = 1,
>>         };
>>  
>>         cpumask_copy(cpus, cpu_active_mask);
> 
> This construct allows for the possibility of power_lb=1,perf_lb=1, does
> that make sense? Why not have a single balance_policy enumeration?

(power_lb == 1 && perf_lb == 1) is incorrect and impossible to have.

(power_lb == 0 && perf_lb == 0) is possible and it means there is no any
balance on this cpu.

So, enumeration is not enough.
> 


-- 
Thanks
    Alex
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