From: Nathan Lynch <ntl@pobox.com>
To: Andi Kleen <ak@suse.de>
Cc: akpm@osdl.org, ak@suse.com, linux-kernel@vger.kernel.org,
linuxppc-dev@ozlabs.org, Paul Jackson <pj@sgi.com>,
Christoph Lameter <clameter@sgi.com>
Subject: Re: Fw: 2.6.16 crashes when running numastat on p575
Date: Mon, 3 Apr 2006 09:18:05 -0500 [thread overview]
Message-ID: <20060403141805.GC25663@localdomain> (raw)
In-Reply-To: <200604031349.03036.ak@suse.de>
Andi Kleen wrote:
> On Monday 03 April 2006 07:15, Paul Jackson wrote:
> > - for (cpu = 0; cpu < NR_CPUS; cpu++) {
> > + for_each_online_cpu(cpu) {
> >
> > Idle curiosity -- what keeps a cpu from going offline during
> > this scan, and leaving us with the same crash as before?
>
>
> CPU hotdown uses RCU like techniques to avoid this. Only potential
> problem could be on a preemptive kernel, but I hope nobody tries
> cpu unplug on such a beast.
I always turn on preempt when testing cpu hotplug (usually on ppc64).
There were several preempt vs cpu hotplug issues until around 2.6.10
or so, iirc, but I think the situation has been stable for a while
now.
WARNING: multiple messages have this Message-ID (diff)
From: Nathan Lynch <ntl@pobox.com>
To: Andi Kleen <ak@suse.de>
Cc: Paul Jackson <pj@sgi.com>,
akpm@osdl.org, linux-kernel@vger.kernel.org,
linuxppc-dev@ozlabs.org, ak@suse.com,
Christoph Lameter <clameter@sgi.com>
Subject: Re: Fw: 2.6.16 crashes when running numastat on p575
Date: Mon, 3 Apr 2006 09:18:05 -0500 [thread overview]
Message-ID: <20060403141805.GC25663@localdomain> (raw)
In-Reply-To: <200604031349.03036.ak@suse.de>
Andi Kleen wrote:
> On Monday 03 April 2006 07:15, Paul Jackson wrote:
> > - for (cpu = 0; cpu < NR_CPUS; cpu++) {
> > + for_each_online_cpu(cpu) {
> >
> > Idle curiosity -- what keeps a cpu from going offline during
> > this scan, and leaving us with the same crash as before?
>
>
> CPU hotdown uses RCU like techniques to avoid this. Only potential
> problem could be on a preemptive kernel, but I hope nobody tries
> cpu unplug on such a beast.
I always turn on preempt when testing cpu hotplug (usually on ppc64).
There were several preempt vs cpu hotplug issues until around 2.6.10
or so, iirc, but I think the situation has been stable for a while
now.
next prev parent reply other threads:[~2006-04-03 14:18 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20060402213216.2e61b74e.akpm@osdl.org>
2006-04-03 5:12 ` Fw: 2.6.16 crashes when running numastat on p575 Christoph Lameter
2006-04-03 5:12 ` Christoph Lameter
2006-04-03 5:15 ` Paul Jackson
2006-04-03 5:15 ` Paul Jackson
2006-04-03 5:25 ` Christoph Lameter
2006-04-03 5:25 ` Christoph Lameter
2006-04-03 6:43 ` Paul Jackson
2006-04-03 6:43 ` Paul Jackson
2006-04-03 14:10 ` Nathan Lynch
2006-04-03 14:10 ` Nathan Lynch
2006-04-03 17:42 ` Christoph Lameter
2006-04-03 17:42 ` Christoph Lameter
2006-04-03 18:01 ` Nathan Lynch
2006-04-03 18:01 ` Nathan Lynch
2006-04-03 18:08 ` Christoph Lameter
2006-04-03 18:08 ` Christoph Lameter
2006-04-03 21:18 ` Andrew Morton
2006-04-03 21:18 ` Andrew Morton
2006-04-04 0:25 ` Paul Jackson
2006-04-04 0:25 ` Paul Jackson
2006-04-03 11:49 ` Andi Kleen
2006-04-03 11:49 ` Andi Kleen
2006-04-03 14:18 ` Nathan Lynch [this message]
2006-04-03 14:18 ` Nathan Lynch
2006-04-03 8:09 ` Sonny Rao
2006-04-03 8:09 ` Sonny Rao
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