From: Nathan Lynch <ntl@pobox•com>
To: Christoph Lameter <clameter@sgi•com>
Cc: akpm@osdl•org, linuxppc-dev@ozlabs•org, Paul Jackson <pj@sgi•com>,
ak@suse•com, linux-kernel@vger•kernel.org
Subject: Re: Fw: 2.6.16 crashes when running numastat on p575
Date: Mon, 3 Apr 2006 13:01:31 -0500 [thread overview]
Message-ID: <20060403180131.GD25663@localdomain> (raw)
In-Reply-To: <Pine.LNX.4.64.0604031039560.20648@schroedinger.engr.sgi.com>
Christoph Lameter wrote:
>
> On Mon, 3 Apr 2006, Nathan Lynch wrote:
>
> > In this case, disabling preempt around the for_each_online_cpu loop
> > would prevent any cpu from going down in the meantime. But since this
> > function doesn't look like it's a hot path, and we're potentially
> > traversing lots of zones and cpus, lock_cpu_hotplug might be preferable.
> >
> > As Paul noted, the fix as it stands isn't adequate.
>
> There are many other for_each_*_cpu loops in the kernel that do not have
> any of the instrumentation you suggest. I suggest you come up with a
> general solution and then go through all of them and fix this. Please be
> aware that many of these loops are performance critical.
But this one isn't, right?
And I'm afraid there's a misunderstanding here -- only
for_each_online_cpu (or accessing the cpu online map in general) has
such restrictions -- for_each_possible_cpu doesn't require any locking
or preempt tricks since cpu_possible_map must not change after boot.
next prev parent reply other threads:[~2006-04-03 18:01 UTC|newest]
Thread overview: 13+ 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 5:15 ` Paul Jackson
2006-04-03 5:25 ` Christoph Lameter
2006-04-03 6:43 ` Paul Jackson
2006-04-03 14:10 ` Nathan Lynch
2006-04-03 17:42 ` Christoph Lameter
2006-04-03 18:01 ` Nathan Lynch [this message]
2006-04-03 18:08 ` Christoph Lameter
2006-04-03 21:18 ` Andrew Morton
2006-04-04 0:25 ` Paul Jackson
2006-04-03 11:49 ` Andi Kleen
2006-04-03 14:18 ` Nathan Lynch
2006-04-03 8:09 ` Sonny Rao
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20060403180131.GD25663@localdomain \
--to=ntl@pobox$(echo .)com \
--cc=ak@suse$(echo .)com \
--cc=akpm@osdl$(echo .)org \
--cc=clameter@sgi$(echo .)com \
--cc=linux-kernel@vger$(echo .)kernel.org \
--cc=linuxppc-dev@ozlabs$(echo .)org \
--cc=pj@sgi$(echo .)com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox