From: Con Kolivas <kernel@kolivas.org>
To: Emmanuel Pacaud <emmanuel.pacaud@univ-poitiers.fr>
Cc: Frederik Deweerdt <deweerdt@free.fr>, linux-kernel@vger.kernel.org
Subject: Re: isolcpus weirdness
Date: Thu, 23 Feb 2006 22:37:13 +1100 [thread overview]
Message-ID: <200602232237.13470.kernel@kolivas.org> (raw)
In-Reply-To: <1140691905.8314.21.camel@localhost.localdomain>
On Thursday 23 February 2006 21:51, Emmanuel Pacaud wrote:
> Le jeudi 23 février 2006 à 21:00 +1100, Con Kolivas a écrit :
> > On Thursday 23 February 2006 20:55, Emmanuel Pacaud wrote:
> > > Le mercredi 22 février 2006 à 22:18 +0100, Frederik Deweerdt a
écrit :
> > > > On Wed, Feb 22, 2006 at 02:21:27PM +0100, Emmanuel Pacaud wrote:
> > > > > What's wrong ?
> > > >
> > > > Are you able to reproduce the same behaviour after disabling HT in
> > > > the kernel config?
> > >
> > > I think HT is disabled in kernel config, since I only see 2 cpus.
> > >
> > > In fact, I've tried to enable HT, but did'nt succeed. HT is enabled in
> > > BIOS, but I'm not sure about exact things I must set at kernel config
> > > level for hyperthreading. I've tried to set/unset CONFIG_SCHED_SMT, but
> > > that changes nothing (no hyperthreading, isolated cpu is always cpu0).
> > >
> > > Here's attached my config file.
> >
> > CONFIG_ACPI is not set
> >
> > You need ACPI to enumerate hyperthread siblings. That's why HT never gets
> > enabled for you.
>
> Following your advice, I've set CONFIG_ACPI, and now, isolcpus works
> fine, when hyperthreading is activated.
>
> But, I'm trying to build a real time system where hyperthreading is not
> desired. So, I've tried to disable HT in BIOS, and the result is the
> same as when ACPI is not enabled in kernel config: isolated cpu is
> always cpu0.
>
> On the same machine, which is originally a Scientific Linux 4, I've
> tried with distribution supplied kernel (a customized 2.6.9 with smp/HT
> enabled): isolcpus works fine, even with HT disabled at BIOS level.
Sorry I was only explaining why hyperthreading wasn't working with your
config. I don't know anything about your problem specifically.
Cheers,
Con
next prev parent reply other threads:[~2006-02-23 11:37 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-02-22 13:21 isolcpus weirdness Emmanuel Pacaud
2006-02-22 21:18 ` Frederik Deweerdt
2006-02-23 9:55 ` Emmanuel Pacaud
2006-02-23 10:00 ` Con Kolivas
2006-02-23 10:51 ` Emmanuel Pacaud
2006-02-23 11:37 ` Con Kolivas [this message]
2006-02-23 12:21 ` Nick Piggin
2006-02-23 13:07 ` Emmanuel Pacaud
2006-02-23 13:30 ` Nick Piggin
2006-02-23 14:03 ` Emmanuel Pacaud
2006-02-24 6:02 ` Nick Piggin
2006-02-24 7:44 ` Emmanuel Pacaud
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