linux-kernel - Re: [BISECTED] "conservative" cpufreq governor broken

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Message-Id: <1254905013.30157.75.camel@eenurkka-desktop>
Date:	Wed, 07 Oct 2009 11:43:33 +0300
From:	Eero Nurkkala <ext-eero.nurkkala@...ia.com>
To:	ext Steven Noonan <steven@...inklabs.net>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Rik van Riel <riel@...hat.com>,
	Venkatesh Pallipadi <venkatesh.pallipadi@...el.com>
Subject: Re: [BISECTED] "conservative" cpufreq governor broken

On Wed, 2009-10-07 at 10:24 +0200, ext Steven Noonan wrote:
> >
> > Steven, how do the cpu loads look like without the patch?
> 
> They're sane:
> 
> [   40.019381] cpufreq load = 100 * (66666 - 66337) / 66666 = 0
> [   40.019396] cpufreq load = 100 * (66666 - 66299) / 66666 = 0
> [   73.352580] cpufreq load = 100 * (66717 - 66349) / 66717 = 0
> [   73.352595] cpufreq load = 100 * (66634 - 63848) / 66634 = 4

Thank you. Could you please try the following:
Now, if ts->nohz_mode == NOHZ_MODE_INACTIVE, ts->inidle is not set
and all subsequent calls from irq_exit() think we weren't idling,
which is not true.

--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -233,6 +233,8 @@ void tick_nohz_stop_sched_tick(int inidle)
 
        now = tick_nohz_start_idle(ts);
 
+       ts->inidle = 1;
+
        /*
         * If this cpu is offline and it is the one which updates
         * jiffies, then give up the assignment and let it be taken by
@@ -248,8 +250,6 @@ void tick_nohz_stop_sched_tick(int inidle)
        if (unlikely(ts->nohz_mode == NOHZ_MODE_INACTIVE))
                goto end;
 
-       ts->inidle = 1;
-
        if (need_resched())
                goto end;
 




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