linux-kernel - Re: x86_64 and AMD with C1E

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Message-ID: <b70f2f960710241426y40d25647v3f25b275fad5ce76@mail.gmail.com>
Date:	Thu, 25 Oct 2007 01:26:38 +0400
From:	"Mikhail Kshevetskiy" <mikhail.kshevetskiy@...il.com>
To:	"Chuck Ebbert" <cebbert@...hat.com>
Cc:	linux-kernel@...r.kernel.org,
	"Thomas Gleixner" <tglx@...utronix.de>
Subject: Re: x86_64 and AMD with C1E

2007/10/19, Chuck Ebbert <cebbert@...hat.com>:
> On 10/01/2007 02:15 AM, Mikhail Kshevetskiy wrote:
> > Hello,
> >
> > I have ASUS F3T notebook with dualcore AMD processor. It has c1e feature
> > enabled. I test linux-2.6.23-rc8-hrt1 kernel. Everything is work (thanks
> > to lapic disable patch), but i have to many processor interrupts per
> > seconds (about 260 additional timer interrupts).
> >
> > The same situation can be observed for linux-2.6.22. Moreover the same
> > problem exist with i386 kernel (test with 2.6.21, 2.6.22, 2.6.22-hrt6,
> > 2.6.23-rc5-hrt1).
> >
> > The problem disappear when I disable c1e on both cores. In this case
> > lapic is not disabled. The back side of this patch is the disabling of
> > all C-state including C1. As result the power consumption increase from
> > 23 (c1e enabled) to 27 (c1e disabled) watts.
> >
> > I fill something wrong here.
> > Is it possible to reduce the amount of timer interrupts?
> > Is it possible to force enable C1,C2 and C3 states when c1e disabled?
> >
>
> How are you disabling C1E?
>
>
dirty hack, i just follow the FreeBSD way and clear C1e bit in lapic
initialization code. I make it for test purpose only, so i do not produce a
patch.

Mikhail
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