From: Andi Kleen <ak@suse.de>
To: Linus Torvalds <torvalds@osdl.org>
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
linux@horizon.com, Kirill Korotaev <dev@sw.ru>,
dada1@cosmosbay.com
Subject: Re: [PATCH] i386 spinlocks should use the full 32 bits, not only 8 bits
Date: 11 Oct 2005 19:59:04 +0200 [thread overview]
Message-ID: <p73ll10rl3r.fsf@verdi.suse.de> (raw)
In-Reply-To: <Pine.LNX.4.64.0510110902130.14597@g5.osdl.org>
Linus Torvalds <torvalds@osdl.org> writes:
> On Tue, 11 Oct 2005, Eric Dumazet wrote:
> >
> > As NR_CPUS might be > 128, and every spining CPU decrements the lock, we need
> > to use more than 8 bits for a spinlock. The current (i386/x86_64)
> > implementations have a (theorical) bug in this area.
I already queued a patch for x86-64 for this for post 2.6.14
following earlier complaints from Eric.
iirc on 32bit there are other issues though like limited
number of reader lock users.
But then I'm not sure why anybody would want to run a 32bit
kernel on such a big machine ...
> I don't think there are any x86 machines with > 128 CPU's right now.
Someone at Unisys just needs to put dual core hyper threaded CPUs
into their 64 socket systems, then you'll have a 256 CPU x86 machine
(which is currently the maximum the APICs can take anyways...)
With Multicores being on everybody's roadmap we'll probably see
such big systems soon.
-Andi
prev parent reply other threads:[~2005-10-11 17:59 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-10-11 4:04 i386 spinlock fairness: bizarre test results Chuck Ebbert
2005-10-11 9:42 ` Eric Dumazet
2005-10-11 13:00 ` Alan Cox
2005-10-11 14:44 ` Linus Torvalds
2005-10-11 15:32 ` [PATCH] i386 spinlocks should use the full 32 bits, not only 8 bits Eric Dumazet
2005-10-11 16:03 ` Linus Torvalds
2005-10-11 16:36 ` Eric Dumazet
2005-10-11 16:54 ` Linus Torvalds
2005-10-11 16:55 ` Linus Torvalds
2005-10-17 7:03 ` Andrew Morton
2005-10-17 7:20 ` Arjan van de Ven
2005-10-20 21:50 ` Ingo Molnar
2005-10-20 21:57 ` Linus Torvalds
2005-10-20 22:02 ` Ingo Molnar
2005-10-20 22:15 ` Linus Torvalds
2005-10-20 22:27 ` Ingo Molnar
2005-10-20 22:44 ` Andrew Morton
2005-10-20 22:53 ` Ingo Molnar
2005-10-20 23:01 ` Andrew Morton
2005-10-20 23:26 ` Ingo Molnar
2005-10-27 16:54 ` Paul Jackson
2005-10-11 17:59 ` Andi Kleen [this message]
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=p73ll10rl3r.fsf@verdi.suse.de \
--to=ak@suse.de \
--cc=dada1@cosmosbay.com \
--cc=dev@sw.ru \
--cc=linux-kernel@vger.kernel.org \
--cc=linux@horizon.com \
--cc=torvalds@osdl.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
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