From: Mathieu Desnoyers <compudj@krystal.dyndns.org>
To: Pavel Machek <pavel@ucw.cz>
Cc: Andrew Morton <akpm@osdl.org>,
Greg Kroah-Hartman <gregkh@suse.de>,
linux-kernel@vger.kernel.org,
"Martin J. Bligh" <mbligh@mbligh.org>,
Christoph Hellwig <hch@infradead.org>,
Douglas Niehaus <niehaus@eecs.ku.edu>,
Ingo Molnar <mingo@redhat.com>,
ltt-dev@shafik.org, systemtap@sources.redhat.com,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [Ltt-dev] [PATCH] local_t : Documentation - update
Date: Tue, 9 Jan 2007 20:06:44 -0500 [thread overview]
Message-ID: <20070110010644.GA8558@Krystal> (raw)
In-Reply-To: <20070110003926.GA27830@Krystal>
* Mathieu Desnoyers (mathieu.desnoyers@polymtl.ca) wrote:
> > So it is "one cpu may write, other cpus may read", and as big as
> > long. Are you sure obscure architectures (sparc?) can implement this
> > in useful way? ... maybe yes, unless obscure architecture exists where
> > second other cpu can see garbage data when first cpu writes into long
> > ...?
> >
> >
>
> Sparc64 uses a memory barrier around the atomic operations in the SMP case
> (see arch/sparc64/lib/atomic.S). The same is true for sparc. As I am not a sparc
> expert, I left the asm-generic default behavior, but I think it should be safe
> to implement local.S code derived from atomic.S to optimize the speed of the
> local_t operations on sparc and sparc64. Can anyone confirm this ?
>
Sorry for the self reply.. looking at arch/sparc/lib/atomic32.c tells me that
local.h could use its own version that would only disable interrupts without
taking any hashed spinlock.
sparc64 seems to be a saner architecture providing atomic operations wrt the
local CPU. A barrier-free version of arch/sparc64/lib/atomic.S would improve
performance.
Mathieu
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prev parent reply other threads:[~2007-01-10 1:06 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-12-21 0:15 [PATCH 0/10] local_t : adding and standardising atomic primitives Mathieu Desnoyers
2006-12-21 0:20 ` [PATCH 1/10] local_t : architecture agnostic Mathieu Desnoyers
2006-12-21 0:21 ` [PATCH 2/10] local_t : alpha Mathieu Desnoyers
2006-12-21 0:22 ` [PATCH 3/10] local_t : i386 Mathieu Desnoyers
2006-12-21 19:44 ` [Ltt-dev] [PATCH 3/10] local_t : i386, local_add_return fix Mathieu Desnoyers
2006-12-21 0:23 ` [PATCH 4/10] local_t : ia64 Mathieu Desnoyers
2006-12-21 0:25 ` [PATCH 5/10] " Mathieu Desnoyers
2006-12-21 14:04 ` [Ltt-dev] [PATCH 5/10] local_t : MIPS Mathieu Desnoyers
2006-12-21 0:25 ` [PATCH 6/10] local_t : parisc Mathieu Desnoyers
2006-12-21 0:27 ` [PATCH 7/10] local_t : powerpc Mathieu Desnoyers
2006-12-21 3:34 ` [Ltt-dev] " Mathieu Desnoyers
2007-01-24 9:08 ` Paul Mackerras
2007-01-24 10:43 ` Gabriel Paubert
2007-01-24 17:00 ` Mathieu Desnoyers
2006-12-21 0:27 ` [PATCH 8/10] local_t : s390 Mathieu Desnoyers
2006-12-21 0:28 ` [PATCH 9/10] local_t : sparc64 Mathieu Desnoyers
2006-12-21 0:29 ` [PATCH 10/10] local_t : x86_64 Mathieu Desnoyers
2006-12-21 19:46 ` [Ltt-dev] [PATCH 10/10] local_t : x86_64 : local_add_return Mathieu Desnoyers
2006-12-23 9:33 ` [PATCH 0/10] local_t : adding and standardising atomic primitives Pavel Machek
2007-01-09 3:14 ` [PATCH] local_t : Documentation Mathieu Desnoyers
2007-01-09 21:01 ` Andrew Morton
2007-01-09 22:06 ` Mathieu Desnoyers
2007-01-09 22:11 ` Andrew Morton
2007-01-09 22:38 ` Pavel Machek
2007-01-09 22:41 ` Pavel Machek
2007-01-09 23:21 ` [PATCH] local_t : Documentation - update Mathieu Desnoyers
2007-01-09 23:45 ` Pavel Machek
2007-01-10 0:39 ` Mathieu Desnoyers
2007-01-10 1:06 ` Mathieu Desnoyers [this message]
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