From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Marcelo Tosatti <marcelo.tosatti@cyclades.com>
Cc: Andi Kleen <ak@suse.de>, Christoph Lameter <clameter@sgi.com>,
linux-kernel@vger.kernel.org, Hugh Dickins <hugh@veritas.com>,
linux-mm@kvack.org
Subject: Re: [RFC 3/6] Make nr_pagecache a per zone counter
Date: Mon, 12 Dec 2005 14:51:13 +1100 [thread overview]
Message-ID: <439CF3B1.4050803@yahoo.com.au> (raw)
In-Reply-To: <20051211204943.GA4375@dmt.cnet>
Marcelo Tosatti wrote:
> On Sun, Dec 11, 2005 at 08:48:40PM +0100, Andi Kleen wrote:
>
>>>By the way, why does nr_pagecache needs to be an atomic variable on UP systems?
>>
>>At least on X86 UP atomic doesn't use the LOCK prefix and is thus quite
>>cheap. I would expect other architectures who care about UP performance
>>(= not IA64) to be similar.
>
>
> But in practice the variable does not need to be an atomic type for UP, but
> simply a word, since stores are atomic on UP systems, no?
>
> Several arches seem to use additional atomicity instructions on
> atomic functions:
>
Yeah, this is to protect from interrupts and is common to most
load store architectures. It is possible we could have
atomic_xxx_irq / atomic_xxx_irqsave functions for these, however
I think nobody has yet demostrated the improvements outweigh the
complexity that would be added.
--
SUSE Labs, Novell Inc.
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next prev parent reply other threads:[~2005-12-12 3:51 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-12-10 0:54 [RFC 0/6] Zoned VM stats Christoph Lameter
2005-12-10 0:54 ` [RFC 1/6] Framework Christoph Lameter
2005-12-10 3:32 ` Andi Kleen
2005-12-12 16:32 ` Christoph Lameter
2005-12-12 3:46 ` Nick Piggin
2005-12-12 3:56 ` Andi Kleen
2005-12-12 4:14 ` Nick Piggin
2005-12-12 4:21 ` Andi Kleen
2005-12-12 4:28 ` Nick Piggin
2005-12-12 4:51 ` Andi Kleen
2005-12-12 7:05 ` Nick Piggin
2005-12-10 0:54 ` [RFC 2/6] Make nr_mapped a per zone counter Christoph Lameter
2005-12-10 0:54 ` [RFC 3/6] Make nr_pagecache " Christoph Lameter
2005-12-11 18:32 ` Marcelo Tosatti
2005-12-11 19:48 ` Andi Kleen
2005-12-11 20:49 ` Marcelo Tosatti
2005-12-12 3:51 ` Nick Piggin [this message]
2005-12-12 11:57 ` Marcelo Tosatti
2005-12-12 16:34 ` Christoph Lameter
2005-12-10 0:55 ` [RFC 4/6] Expanded node and zone statistics Christoph Lameter
2005-12-10 0:55 ` [RFC 5/6] Make nr_slab a per zone counter Christoph Lameter
2005-12-10 0:55 ` [RFC 6/6] Make nr_pagecache " Christoph Lameter
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