From: Andi Kleen <ak@suse.de>
To: Christoph Lameter <clameter@sgi.com>
Cc: David Howells <dhowells@redhat.com>,
Nick Piggin <nickpiggin@yahoo.com.au>,
Arjan van de Ven <arjan@infradead.org>,
Dong Feng <middle.fengdong@gmail.com>,
Paul Mackerras <paulus@samba.org>,
linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org
Subject: Re: Why Semaphore Hardware-Dependent?
Date: Tue, 29 Aug 2006 19:22:04 +0200 [thread overview]
Message-ID: <200608291922.04354.ak@suse.de> (raw)
In-Reply-To: <Pine.LNX.4.64.0608290855510.18031@schroedinger.engr.sgi.com>
On Tuesday 29 August 2006 17:56, Christoph Lameter wrote:
> On Tue, 29 Aug 2006, David Howells wrote:
>
> > Because i386 (and x86_64) can do better by using XADDL/XADDQ.
>
> And Ia64 would like to use fetchadd....
This might be a dumb question, but I would expect even on altix
with lots of parallel faulting threads rwsem performance be basically
limited by aquiring the cache line and releasing it later to another CPU.
Do you really think it will make much difference what particular atomic
operation is used? The basic cost of sending the cache line over the
interconnect should be all the same, no? And once the cache line is local
it should be reasonably fast either way.
> > CMPXCHG is not available on all archs, and may not be implemented on all archs
> > through other atomic instructions.
>
> Which arches do not support cmpxchg?
parisc at least iirc (it practically doesn't support very much atomically)
and likely sparcv8.
-Andi
next prev parent reply other threads:[~2006-08-29 17:25 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-08-27 19:22 Why Semaphore Hardware-Dependent? Dong Feng
2006-08-27 20:52 ` Andi Kleen
2006-08-27 21:05 ` Christoph Lameter
2006-08-27 21:39 ` Andi Kleen
2006-08-27 22:14 ` Christoph Lameter
2006-08-28 0:18 ` Paul Mackerras
2006-08-28 5:14 ` Chris Wedgwood
2006-08-28 5:21 ` Christoph Lameter
2006-08-28 5:56 ` Jan Engelhardt
2006-08-28 12:35 ` linux-os (Dick Johnson)
2006-08-28 7:23 ` Andi Kleen
2006-08-29 1:00 ` Paul Mackerras
2006-08-28 7:30 ` Arjan van de Ven
2006-08-29 1:18 ` Nick Piggin
2006-08-29 6:07 ` Andi Kleen
2006-09-13 17:54 ` Nick Piggin
2006-08-29 10:05 ` David Howells
2006-08-29 10:56 ` Andi Kleen
2006-08-29 17:40 ` Andrew Morton
2006-08-29 19:10 ` Benjamin LaHaise
2006-08-29 15:56 ` Christoph Lameter
2006-08-29 16:20 ` Ralf Baechle
2006-08-29 16:25 ` David Howells
2006-08-29 16:28 ` Christoph Lameter
2006-08-29 16:57 ` David Howells
2006-08-29 16:53 ` Ralf Baechle
2006-08-29 16:58 ` Geert Uytterhoeven
2006-08-29 17:22 ` Andi Kleen [this message]
2006-08-29 17:36 ` Christoph Lameter
2006-08-29 18:18 ` Andi Kleen
2006-08-29 18:30 ` David Howells
2006-08-29 18:33 ` Andi Kleen
2006-08-29 18:56 ` David Howells
2006-08-29 18:41 ` Christoph Lameter
2006-09-13 18:04 ` Nick Piggin
2006-09-13 18:07 ` Christoph Lameter
2006-09-13 18:13 ` Nick Piggin
2006-09-13 18:16 ` Christoph Lameter
2006-09-13 18:50 ` David Howells
2006-09-13 19:25 ` Nick Piggin
2006-09-14 11:41 ` David Howells
2006-09-14 15:27 ` Nick Piggin
2006-09-14 15:38 ` Nick Piggin
2006-09-15 8:59 ` David Howells
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