From: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
To: Alexey Dobriyan <adobriyan@gmail.com>
Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
Adrian Bunk <bunk@stusta.de>, Andi Kleen <andi@firstfloor.org>
Subject: Re: [patch 4/8] Immediate Value - Add kconfig menus
Date: Sat, 14 Jul 2007 11:27:34 -0400 [thread overview]
Message-ID: <20070714152734.GB4737@Krystal> (raw)
In-Reply-To: <20070714072801.GB5822@martell.zuzino.mipt.ru>
* Alexey Dobriyan (adobriyan@gmail.com) wrote:
> On Fri, Jul 13, 2007 at 09:24:43PM -0400, Mathieu Desnoyers wrote:
> > Immediate values provide a way to use dynamic code patching to update variables
> > sitting within the instruction stream. It saves caches lines normally used by
> > static read mostly variables.
>
> > kernel/Kconfig.immediate | 11 +++++++++++
>
> NAK, if this immediate stuff is so super-cool¹ it should be default on.
>
> ¹ it isn't
>
Hi Alexey,
On embedded systems, the tradeoff is not the same. The immediate values
trade a little bit of system memory (to keep the pointers to the
variable and instruction as well as the size of the variable, only used
when the variable is updated) in order to remove cache line hot paths.
Also, embedded systems with physically read-only memory clearly does not
want to enable this.
Mathieu
--
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
next prev parent reply other threads:[~2007-07-14 15:27 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-07-14 1:24 [patch 0/8] Immediates Values (real variables) Mathieu Desnoyers
2007-07-14 1:24 ` [patch 1/8] Immediate values - Global modules list and module mutex Mathieu Desnoyers
2007-07-14 1:24 ` [patch 2/8] Immediate Value - Architecture Independent Code Mathieu Desnoyers
2007-07-14 16:24 ` Christoph Hellwig
2007-07-14 22:59 ` [PATCH] Immediate Values - Architecture Independent Code - Fixes following HCH comments Mathieu Desnoyers
2007-07-15 1:36 ` [PATCH] Immediate Values - Architecture Independent Code - kerneldoc Mathieu Desnoyers
2007-07-15 23:40 ` [PATCH] Immediate Values - Architecture Independent Code - kerneldoc for implementation Mathieu Desnoyers
2007-07-14 23:52 ` [PATCH] Immediate Value - Architecture Independent Code Deferred Sync Mathieu Desnoyers
2007-07-15 1:32 ` Mathieu Desnoyers
2007-07-14 1:24 ` [patch 3/8] Immediate Values - Non Optimized Architectures Mathieu Desnoyers
2007-07-14 23:01 ` Mathieu Desnoyers
2007-07-14 1:24 ` [patch 4/8] Immediate Value - Add kconfig menus Mathieu Desnoyers
2007-07-14 7:28 ` Alexey Dobriyan
2007-07-14 15:27 ` Mathieu Desnoyers [this message]
2007-07-16 0:33 ` Andi Kleen
2007-07-16 0:41 ` Mathieu Desnoyers
2007-07-16 0:32 ` Mathieu Desnoyers
2007-07-16 0:34 ` [PATCH] Immediate Value - Kconfig menu in EMBEDDED Mathieu Desnoyers
2007-07-14 1:24 ` [patch 5/8] Immediate Values - kprobe header fix Mathieu Desnoyers
2007-07-14 16:26 ` Christoph Hellwig
2007-07-14 23:01 ` Mathieu Desnoyers
2007-07-14 23:04 ` [PATCH] Immediate Values - Move Kprobes i386 restore_interrupt to kdebug.h Mathieu Desnoyers
2007-07-14 1:24 ` [patch 6/8] Immediate Value - i386 Optimization Mathieu Desnoyers
2007-07-14 23:08 ` [PATCH] Immediate Values - Pre Fix " Mathieu Desnoyers
2007-07-15 1:37 ` [PATCH] Immediate Values - i386 Optimization - kerneldoc Mathieu Desnoyers
2007-07-15 23:41 ` [PATCH] Immediate Values - i386 Optimization - kerneldoc for implementation Mathieu Desnoyers
2007-07-14 1:24 ` [patch 7/8] Immediate Value - PowerPC Optimization Mathieu Desnoyers
2007-07-14 23:09 ` [PATCH] Immediate Values - Pre fix powerpc Optimization Mathieu Desnoyers
2007-07-15 1:38 ` [PATCH] Immediate Values - PowerPC Optimization - kerneldoc Mathieu Desnoyers
2007-07-15 23:42 ` [PATCH] Immediate Values - PowerPC Optimization - kerneldoc for implementation Mathieu Desnoyers
2007-07-14 1:24 ` [patch 8/8] Immediate Value - Documentation Mathieu Desnoyers
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