From: "H. Peter Anvin" <hpa@zytor.com>
To: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Ingo Molnar <mingo@elte.hu>, Andi Kleen <andi@firstfloor.org>,
Alexander van Heukelum <heukelum@fastmail.fm>,
Cyrill Gorcunov <gorcunov@gmail.com>,
Alexander van Heukelum <heukelum@mailshack.com>,
LKML <linux-kernel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
lguest@ozlabs.org, jeremy@xensource.com,
Steven Rostedt <srostedt@redhat.com>,
Mike Travis <travis@sgi.com>
Subject: Re: [PATCH RFC/RFB] x86_64, i386: interrupt dispatch changes
Date: Thu, 13 Nov 2008 17:20:08 -0800 [thread overview]
Message-ID: <491CD248.8030209@zytor.com> (raw)
In-Reply-To: <200811141211.23496.nickpiggin@yahoo.com.au>
Nick Piggin wrote:
>
> I heard from an Intel hardware engineer that Nehalem has some
> really fancy logic in it to make locked instructions "free", that
> was nacked from earlier CPUs because it was too costly. So obviously
> it is taking a fair whack of transistors or power for them to do it.
> And even then it is far from free, but still seems to be one or two
> orders of magnitude more expensive than a regular instruction.
>
Last I heard it was still a dozen-ish cycles even on Nehalem.
>
> IMO, we shouldn't stop bothering about LOCK prefix in the forseeable
> future.
>
Even if a CPU came out *today* that had zero-cost locks we'd have to
worry about it for at least another 5-10 years. The good news is that
we're doing pretty good with it for now, but I don't believe in general
we can avoid the fact that improving LOCK performance helps everything
when you're dealing with large numbers of cores/threads.
-hpa
next prev parent reply other threads:[~2008-11-14 1:30 UTC|newest]
Thread overview: 83+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-11-04 12:28 [PATCH RFC/RFB] x86_64, i386: interrupt dispatch changes Alexander van Heukelum
2008-11-04 12:42 ` Ingo Molnar
2008-11-04 13:29 ` Alexander van Heukelum
2008-11-04 14:00 ` Ingo Molnar
2008-11-04 16:23 ` Alexander van Heukelum
2008-11-04 16:47 ` Cyrill Gorcunov
2008-11-04 16:58 ` Ingo Molnar
2008-11-04 17:13 ` Cyrill Gorcunov
2008-11-04 17:29 ` Alexander van Heukelum
2008-11-06 9:19 ` Ingo Molnar
2008-11-04 20:02 ` Jeremy Fitzhardinge
2008-11-04 20:15 ` H. Peter Anvin
2008-11-04 20:02 ` Jeremy Fitzhardinge
2008-11-04 15:07 ` Cyrill Gorcunov
2008-11-04 15:47 ` Alexander van Heukelum
2008-11-04 16:36 ` Ingo Molnar
2008-11-04 16:45 ` Alexander van Heukelum
2008-11-04 16:54 ` Ingo Molnar
2008-11-04 16:55 ` Ingo Molnar
2008-11-04 16:58 ` Alexander van Heukelum
2008-11-04 17:39 ` Alexander van Heukelum
2008-11-04 17:05 ` Andi Kleen
2008-11-04 18:06 ` Alexander van Heukelum
2008-11-04 18:14 ` H. Peter Anvin
2008-11-04 18:44 ` Alexander van Heukelum
2008-11-04 19:07 ` H. Peter Anvin
2008-11-04 19:33 ` H. Peter Anvin
2008-11-04 20:06 ` Jeremy Fitzhardinge
2008-11-04 20:30 ` Andi Kleen
2008-11-04 20:26 ` H. Peter Anvin
2008-11-04 20:46 ` Andi Kleen
2008-11-04 20:44 ` Ingo Molnar
2008-11-04 21:06 ` Andi Kleen
2008-11-05 0:42 ` Jeremy Fitzhardinge
2008-11-05 0:50 ` H. Peter Anvin
2008-11-06 9:15 ` Ingo Molnar
2008-11-06 9:25 ` H. Peter Anvin
2008-11-06 9:30 ` Ingo Molnar
2008-11-05 10:26 ` Ingo Molnar
2008-11-14 1:11 ` Nick Piggin
2008-11-14 1:20 ` H. Peter Anvin [this message]
2008-11-14 2:12 ` Nick Piggin
2008-11-04 21:29 ` Ingo Molnar
2008-11-04 21:35 ` H. Peter Anvin
2008-11-04 21:52 ` Ingo Molnar
2008-11-05 17:53 ` Cyrill Gorcunov
2008-11-05 18:04 ` H. Peter Anvin
2008-11-05 18:14 ` Cyrill Gorcunov
2008-11-05 18:20 ` H. Peter Anvin
2008-11-05 18:26 ` Cyrill Gorcunov
[not found] ` <1226243805.27361.1283784629@webmail.messagingengine.com>
2008-11-10 1:29 ` H. Peter Anvin
2008-11-26 21:35 ` [Lguest] " Avi Kivity
2008-11-26 21:50 ` Avi Kivity
2008-11-27 0:03 ` H. Peter Anvin
2008-11-27 10:13 ` Avi Kivity
2008-11-27 10:56 ` Andi Kleen
2008-11-27 10:59 ` Avi Kivity
2008-11-28 20:48 ` Alexander van Heukelum
2008-11-29 15:45 ` Alexander van Heukelum
2008-11-29 18:21 ` Avi Kivity
2008-11-29 18:22 ` Avi Kivity
2008-11-29 19:58 ` Ingo Molnar
2008-12-01 4:32 ` Rusty Russell
2008-12-01 8:00 ` Ingo Molnar
2008-12-01 9:24 ` Avi Kivity
2008-12-01 10:32 ` Cyrill Gorcunov
2008-12-01 10:41 ` Avi Kivity
2008-12-01 10:49 ` Ingo Molnar
2008-11-10 8:58 ` Ingo Molnar
2008-11-10 12:44 ` Alexander van Heukelum
2008-11-10 13:07 ` Ingo Molnar
2008-11-10 21:35 ` Alexander van Heukelum
2008-11-10 22:21 ` H. Peter Anvin
2008-11-11 5:00 ` H. Peter Anvin
2008-11-13 22:23 ` Matt Mackall
2008-11-14 1:18 ` H. Peter Anvin
2008-11-14 2:29 ` Matt Mackall
2008-11-14 3:22 ` H. Peter Anvin
2008-11-11 9:54 ` Ingo Molnar
2008-11-10 15:39 ` H. Peter Anvin
2008-11-10 21:44 ` Alexander van Heukelum
2008-11-10 23:34 ` H. Peter Anvin
2008-11-05 18:15 ` Cyrill Gorcunov
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