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From: Manuel Lauss <mano@roarinelk.homelinux.net>
To: Ralf Baechle <ralf@linux-mips.org>
Cc: Linux-MIPS <linux-mips@linux-mips.org>
Subject: Re: [PATCH 2/2] Alchemy: provide cpu feature overrides.
Date: Tue, 23 Dec 2008 17:29:54 +0100	[thread overview]
Message-ID: <20081223172954.06b301cb@scarran.roarinelk.net> (raw)
In-Reply-To: <20081223143909.GD5981@linux-mips.org>

On Tue, 23 Dec 2008 15:39:09 +0100
Ralf Baechle <ralf@linux-mips.org> wrote:

> On Mon, Dec 22, 2008 at 08:21:08PM +0100, Manuel Lauss wrote:
> 
> > Add cpu feature override constants for Alchemy.
> > 
> > Code generated for Alchemy does not use all MIPS32r1 features.  Add cpu
> > feature overrides tailored for Alchemy chips and help GCC create better
> > code.  As a nice sideeffect the size of the resulting kernel is reduced
> > by a few kilobytes (~200kB for a non-modular db1200 devboard build).
> 
> The enormous size difference is probably 99% due to atomic and bitops
> which exist in LL/SC and non-LL/SC versions and without the header gcc
> will expand the inline function each time.  That will hurt, also
> performance.  Also the big size difference suggests that we may want to
> outline some or all of these functions.

You are of course correct:

   text    data     bss     dec     hex filename                                                                                                                
3890074  124400  436528 4451002  43eaba vmlinux                                                                                                                 
3890070  124400  436528 4450998  43eab6 vmlinux+mips32r1
3690742  124396  436528 4251666  40e012 vmlinux++llsc
3666386  124332  436528 4227246  4080ae vmlinux+++all

-- ml.

  reply	other threads:[~2008-12-23 16:29 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-12-22 19:21 [PATCH 1/2] Alchemy: MIPS hazard workarounds are not required Manuel Lauss
2008-12-22 19:21 ` [PATCH 2/2] Alchemy: provide cpu feature overrides Manuel Lauss
2008-12-23 14:39   ` Ralf Baechle
2008-12-23 16:29     ` Manuel Lauss [this message]
2008-12-23 16:37       ` Ralf Baechle
2008-12-23 21:15         ` Manuel Lauss

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