Message-Id: <4t16i2$13154k@orsmga001.jf.intel.com>
From: "Chen, Kenneth W" <kenneth.w.chen@intel.com>
To: "'Con Kolivas'" <kernel@kolivas.org>
Cc: <tim.c.chen@linux.intel.com>, <linux-kernel@vger.kernel.org>,
       <mingo@elte.hu>, "Andrew Morton" <akpm@osdl.org>
Subject: RE: Regression seen for patch "sched:dont decrease idle sleep avg"
Date: Mon, 15 May 2006 18:22:24 -0700
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Con Kolivas wrote on Monday, May 15, 2006 4:45 PM
> On Tuesday 16 May 2006 05:01, Chen, Kenneth W wrote:
> > I don't think the if and the else block is doing the same thing. In the if
> > block, the p->sleep_avg is unconditionally boosted to ceiling for all
> > tasks, though it will not reduce sleep_avg for tasks that already exceed
> > the ceiling. Bumping up sleep_avg will then translate into priority boost
> > of MAX_BONUS-1, which potentially can be too high.
> 
> Yes it's only designed to detect something that has been asleep for an 
> arbitrary long time and "categorised as idle"; it is not supposed to be a 
> priority stepping stone for everything, in this case at MAX_BONUS-1. Mike 
> proposed doing this instead, but it was never my intent. Your comment is not 
> quite correct as it just happens to be MAX_BONUS-1 at nice 0, and not any 
> other nice value.

Huh??

sleep_avg is set at constant:
p->sleep_avg = JIFFIES_TO_NS(MAX_SLEEP_AVG - DEF_TIMESLICE);


The bonus calculation is:

#define CURRENT_BONUS(p) \
        (NS_TO_JIFFIES((p)->sleep_avg) * MAX_BONUS / MAX_SLEEP_AVG)

bonus = CURRENT_BONUS(p) - MAX_BONUS / 2;

None of the calculation that I see uses nice value.  Did I miss something?

- Ken
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