linux-kernel - Re: [PATCH 1/2] Add scaled time to taskstats based process accounting

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Date:	Fri, 17 Aug 2007 10:17:46 +0530
From:	Balbir Singh <balbir@...ux.vnet.ibm.com>
To:	Michael Neuling <mikey@...ling.org>
CC:	Paul Mackerras <paulus@...ba.org>, Andrew Morton <akpm@...l.org>,
	linuxppc-dev@...abs.org, linux-kernel@...r.kernel.org,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>
Subject: Re: [PATCH 1/2] Add scaled time to taskstats based process accounting

Michael Neuling wrote:
>> I'd also request for you to add a cpu_scaled_run_real_total for use
>> by delay accounting. cpu_scaled_run_real_total should be similar in
>> functionality to cpu_run_real_total.
> 
> Will do.  Should I add cpu_scaled_run_real_total to the end of the
> struct taskstat, or next to cpu_run_real_total?
> 

Please add it to the end, that helps maintain binary compatibility
across all versions of taskstats.

>>>  	/* Note: this timer irq context must be accounted for as well. */
>>> -	if (user_tick)
>>> +	if (user_tick) {
>>>  		account_user_time(p, jiffies_to_cputime(1));
>>> -	else
>>> +		account_user_time_scaled(p, jiffies_to_cputime(1));
>>> +	} else {
>>>  		account_system_time(p, HARDIRQ_OFFSET, jiffies_to_cputime(1));
>>> +		account_system_time_scaled(p, jiffies_to_cputime(1));
>>> +	}
>> I am a little confused here, scaled accounting and regular accounting
>> go hand in hand?
> 
> We need to account for scaled and normal time in this generic code.
> All other calls to account_(user|system)_time are in arch code.  
> 

So the assumption here is that we ran at full frequency during
this time, is my understanding correct?

-- 
	Warm Regards,
	Balbir Singh
	Linux Technology Center
	IBM, ISTL
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