From: Mikael Pettersson <mikpe@csd.uu.se>
To: "J.A. Magallon" <jamagallon@able.es>
Cc: Frank Cusack <fcusack@fcusack.com>, lkml <linux-kernel@vger.kernel.org>
Subject: Re: 2nd proc not seen
Date: Mon, 29 Sep 2003 11:13:21 +0200 [thread overview]
Message-ID: <16247.63409.996071.860727@gargle.gargle.HOWL> (raw)
In-Reply-To: <20030929085807.GA22884@werewolf.able.es>
J.A. Magallon writes:
>
> On 09.29, Frank Cusack wrote:
> > On Thu, Sep 04, 2003 at 09:14:37AM -0700, Frank Cusack wrote:
> > > On Thu, Sep 04, 2003 at 02:11:13AM -0700, Frank Cusack wrote:
> > > > I think I've seen some recent talk about this problem. I have an HPAQ
> > > > xw6000 w/ 2xP4 CPUs. A RH kernel finds both CPUs (4 if I enable HT). A
> > > > kernel.org kernel only finds 1 (2 if I enable HT).
> >
> > This turned out to be a CPU numbering issue. The HPAQ machine numbers
> > the cpus #0 and #6. I had NR_CPUS set to 2. That only works if the CPUs
> > are physically numbered 0 and 1.
> >
> > So NR_CPUS is a little misleading. I could suggest a Config.help change
> > if you like.
> >
>
> This is a little weird. This forces you to have all the SMP structures sized
> 8 just to use 2 members.
>
> Was not there a physical-logical map ? Or that was in -aa kernel and 2.6 ?
Problem #1 is that physical CPU numbering isn't dense. This is not a bug.
Problem #2 is that the kernel's internal dense-logical-to-sparse-physical
numbering was deleted in 2.5.23 or thereabouts.
Hence NR_CPUS is basically impossible to use reliably in 2.6 unless we
reintroduce cpu_logical_map[].
/Mikael
next prev parent reply other threads:[~2003-09-29 9:13 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-09-04 9:11 2nd proc not seen Frank Cusack
2003-09-04 16:14 ` Frank Cusack
2003-09-29 3:50 ` Frank Cusack
2003-09-29 8:58 ` J.A. Magallon
2003-09-29 9:13 ` Mikael Pettersson [this message]
2003-09-29 20:51 ` William Lee Irwin III
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