From: Christoph Lameter <cl@linux.com>
To: Sam Ravnborg <sam@ravnborg.org>
Cc: Tim Abbott <tabbott@MIT.EDU>, Anders Kaseorg <andersk@MIT.EDU>,
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Yoshinori Sato <ysato@users.sourceforge.jp>
Subject: Re: [PATCH 6/6] Add support for __read_mostly to linux/cache.h
Date: Fri, 1 May 2009 09:52:18 -0400 (EDT) [thread overview]
Message-ID: <alpine.DEB.1.10.0905010948140.18324@qirst.com> (raw)
In-Reply-To: <20090501094407.GD18326@uranus.ravnborg.org>
On Fri, 1 May 2009, Sam Ravnborg wrote:
> Are there any specific reason why we do not support read_mostly on all
> architectures?
Not that I know of.
> read_mostly is about grouping rarely written data together
> so what is needed is to introduce this section in the remaining
> archtectures.
>
> Christoph - git log says you did the inital implmentation.
> Do you agree?
Yes.
There is some concern that __read_mostly is needlessly applied to
numerous variables that are not used in hot code paths. This may make
__read_mostly ineffective and actually increase the cache footprint of a
function since global variables are no longer in the same cacheline. If
such a function is called and the caches are cold then two cacheline
fetches have to be done instead of one.
next prev parent reply other threads:[~2009-05-01 13:52 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-04-30 19:32 [PATCH 0/6] macros for section name cleanup Tim Abbott
2009-04-30 19:32 ` [PATCH 1/6] Add new macros for page-aligned data and bss sections Tim Abbott
2009-04-30 19:32 ` [PATCH 2/6] Add new NOSAVE_DATA linker script macro Tim Abbott
2009-04-30 19:32 ` [PATCH 3/6] Add new CACHELINE_ALIGNED_DATA " Tim Abbott
2009-04-30 19:32 ` [PATCH 4/6] Add new INIT_TASK_DATA() " Tim Abbott
2009-04-30 19:32 ` [PATCH 5/6] Add new READ_MOSTLY_DATA(align) " Tim Abbott
2009-04-30 19:32 ` [PATCH 6/6] Add support for __read_mostly to linux/cache.h Tim Abbott
2009-05-01 9:44 ` Sam Ravnborg
2009-05-01 13:52 ` Christoph Lameter [this message]
2009-05-01 21:47 ` [microblaze-uclinux] " Edgar E. Iglesias
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