From: Andi Kleen <ak@suse.de>
To: Arjan van de Ven <arjan@linux.intel.com>
Cc: linux-kernel@vger.kernel.org, torvalds@osdl.org, akpm@osdl.org
Subject: Re: [Patch 4/4] Tell GCC 4.1 to move unlikely() code to a separate section
Date: Mon, 27 Feb 2006 16:39:34 +0100 [thread overview]
Message-ID: <200602271639.34776.ak@suse.de> (raw)
In-Reply-To: <1141054284.2992.136.camel@laptopd505.fenrus.org>
On Monday 27 February 2006 16:31, Arjan van de Ven wrote:
> This patch is more controversial I assume; it offers the option
> to use the gcc 4.1 option to move unlikely() code to a separate section.
> On the con side, this means that longer byte sequences are needed to jump
> to this code, on the Pro side it means that the unlikely() code isn't sharing
> icache cachelines and tlbs anymore.
I don't think this will do anything because the default Makefile
still has
CFLAGS += -fno-reorder-blocks
That was me because it made assembly debugging much easier. I would be willing
to reconsider this if you can give me some hard data just from this change:
- benchmark changes
- .text size increase
Also I don't like it being an separate CONFIG options. We already have too many
obscure ones. Either it should be on by default or not there at all.
-Andi
next prev parent reply other threads:[~2006-02-27 15:42 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-02-27 15:23 [Patch 0/4] Reordering of functions, try 2 Arjan van de Ven
2006-02-27 15:27 ` [Patch 2/4] Basic reorder infrastructure Arjan van de Ven
2006-02-27 15:41 ` Andi Kleen
2006-02-27 16:31 ` sam
2006-02-27 17:19 ` Arjan van de Ven
2006-02-28 19:08 ` Sam Ravnborg
2006-03-10 9:45 ` [Patch 2/4] Basic reorder infrastructure - makes linking very slow Andi Kleen
2006-02-27 15:31 ` [Patch 4/4] Tell GCC 4.1 to move unlikely() code to a separate section Arjan van de Ven
2006-02-27 15:39 ` Andi Kleen [this message]
2006-02-27 23:33 ` Bill Davidsen
2006-02-27 15:31 ` [Patch 3/4] Move the base kernel to 2Mb to align with TLB boundaries Arjan van de Ven
2006-02-27 15:36 ` Andi Kleen
2006-02-27 15:52 ` Arjan van de Ven
2006-02-27 15:31 ` [Patch 1/4] avoid entry.S functions from reordering Arjan van de Ven
2006-02-27 15:36 ` [Patch 0/4] Reordering of functions, try 2 Andi Kleen
2006-02-27 15:43 ` Arjan van de Ven
-- strict thread matches above, loose matches on Subject: below --
2006-02-28 6:34 [Patch 4/4] Tell GCC 4.1 to move unlikely() code to a separate section Chuck Ebbert
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