linux-kernel - Re: [BUG][2.6.30] Niced processes do not raise CPU frequency with ondemand

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Message-Id: <1244828508.4534.1404.camel@localhost.localdomain>
Date:	Fri, 12 Jun 2009 10:41:48 -0700
From:	"Pallipadi, Venkatesh" <venkatesh.pallipadi@...el.com>
To:	Frans Pop <elendil@...net.nl>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>
Subject: Re: [BUG][2.6.30] Niced processes do not raise CPU frequency with
 ondemand

On Fri, 2009-06-12 at 10:25 -0700, Frans Pop wrote:
> Thanks for the quick reply Venki.
> 
> On Friday 12 June 2009, Pallipadi, Venkatesh wrote:
> > What does ignore_nice under cpufreq/ondemand say?
> 
> Right, that's 1 (was not aware that existed :-P)
> And changing it to 0 solves the problem.

OK. Good to know that there are no kernel bugs with honoring
ignore_nice_load setting. :)

> Next question is: how and why does it get set?
> As userland has not changed (AFAIK), my first suspect remains the kernel.
> 

Kernel never sets this. It is initialized to 0 and provides a /sys
interface to user. I think it is set by some user app
(gnome-power-manager or some other app like that). That explains why it
is 0 initially after boot and gets changed later.

The support for ignore_nice_load=1 was broken in kernel for a short
while (arounf 2.6.28, IIRC). That may be the reason why this behavior
was not noticed earlier.

Thanks,
Venki

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