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From: Andi Kleen <ak@suse.de>
To: Dave Jones <davej@redhat.com>, linux-kernel@vger.kernel.org, ak@suse.de
Subject: Re: for_each_online_cpu broken ?
Date: Thu, 8 Dec 2005 06:26:32 +0100	[thread overview]
Message-ID: <20051208052632.GF11190@wotan.suse.de> (raw)
In-Reply-To: <20051208050738.GE24356@redhat.com>

On Thu, Dec 08, 2005 at 12:07:39AM -0500, Dave Jones wrote:
> Whilst debugging a memory leak, I hit sysrq meminfo,
> and got hot/cold info for CONFIG_NR_CPUS rather than 4 cpus
> I fixed a bug recently in mm/page_alloc.c to change this from
> a for_each_cpu to a for_each_online_cpu and I'm pretty certain
> I tested that it worked, but for reasons unknown, it's now
> misbehaving again.
> 
> I've only tried reproducing this on x86-64 so far.

If the online map is wrong all kinds of things would go wrong.

Most likely your kernel doesn't have the fix.

The possible map is fixed kind of BTW in 2.6.15rc*. It was a side effect
of CPU hotplug, which now uses a better algorithm to guess the 
number of possible CPUs. In 2.6.15 you will just get half the number
of available CPUs in addition by default

-Andi

  reply	other threads:[~2005-12-08  5:26 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-12-08  5:07 Dave Jones
2005-12-08  5:26 ` Andi Kleen [this message]
2005-12-08  5:33   ` Dave Jones
2005-12-08  5:38     ` David S. Miller
2005-12-08  6:12       ` Andi Kleen
2005-12-08  6:27         ` Dave Jones
2005-12-08  6:22     ` Nigel Cunningham
2005-12-08  6:28       ` Dave Jones
2005-12-08  6:30         ` Andi Kleen
2005-12-09  0:03         ` Nigel Cunningham
2005-12-08  6:30     ` Andi Kleen
2005-12-08  6:43       ` Dave Jones

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