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From: Andrew Morton <akpm@digeo.com>
To: Akira Tsukamoto <at541@columbia.edu>
Cc: linux-kernel@vger.kernel.org, Hirokazu Takahashi <taka@valinux.co.jp>
Subject: Re: [PATCH] 2/2 2.5.45 cleanup & add original copy_ro/from_user
Date: Sat, 02 Nov 2002 10:13:46 -0800	[thread overview]
Message-ID: <3DC415DA.29D22E92@digeo.com> (raw)
In-Reply-To: 20021102060423.032A.AT541@columbia.edu

Akira Tsukamoto wrote:
> 
> On Sat, 02 Nov 2002 02:32:32 -0800
> Andrew Morton <akpm@digeo.com> mentioned:
> 
> > Akira Tsukamoto wrote:
> > >
> > But you've inlined them again.  Your patches increase my kernel
> > size by 17 kbytes, which is larger than my entire Layer 1 instruction
> > cache!
> 
> It is because I was working on this patch based on 2.5.44 :)
> 
> As Andi mentioned, how about selecting if OCNFIG_SAMLL is defined?

Well you could make it dependent on CONFIG_SLOW_KERNEL ;)

It's an act of faith - we have no benchmarks on this.  But it
goes like this:

- subroutine calls are fast
- cache misses are slow
- kernel has no right to be evicting user code from the CPU cache
- smaller is faster
- inlining to the point of increasing code size is probably wrong

  reply	other threads:[~2002-11-02 18:07 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2002-11-02  8:06 [PATCH] 2/2 2.5.45 cleanup & add original copy_ro/from_user Akira Tsukamoto
2002-11-02 10:32 ` Andrew Morton
2002-11-02 11:07   ` Akira Tsukamoto
2002-11-02 18:13     ` Andrew Morton [this message]
2002-11-03  2:43       ` Akira Tsukamoto
2002-11-03  4:04         ` Andrew Morton
2002-11-03  2:43       ` Akira Tsukamoto
2002-11-03  2:57   ` Akira Tsukamoto
2002-11-03 21:24     ` Dave Jones
2002-11-03 22:22       ` Andries Brouwer
     [not found] <20021102025838.220E.AT541@columbia.edu.suse.lists.linux.kernel>
     [not found] ` <3DC3A9C0.7979C276@digeo.com.suse.lists.linux.kernel>
2002-11-02 10:58   ` Andi Kleen
2002-11-02 11:03     ` Andrew Morton
2002-11-02 16:55     ` Denis Vlasenko
2002-11-02 12:09       ` Andi Kleen
2002-11-02 17:08         ` Denis Vlasenko
2002-11-02 12:23           ` Andi Kleen
  -- strict thread matches above, loose matches on Subject: below --
2002-11-04  3:36 Akira Tsukamoto

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