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From: Andrew Morton <akpm@linux-foundation.org>
To: Michal Nazarewicz <mina86@mina86.com>
Cc: Steven Rostedt <rostedt@goodmis.org>,
	Hagen Paul Pfeifer <hagen@jauu.net>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] include: kernel.h: rewrite min3, max3 and clamp using min and max
Date: Mon, 16 Jun 2014 16:18:04 -0700	[thread overview]
Message-ID: <20140616161804.bb06ed842f59371c031d1252@linux-foundation.org> (raw)
In-Reply-To: <1402952842-12886-1-git-send-email-mina86@mina86.com>

On Mon, 16 Jun 2014 23:07:22 +0200 Michal Nazarewicz <mina86@mina86.com> wrote:

> It appears that gcc is better at optimising a double call to min
> and max rather than open coded min3 and max3.  This can be observed
> here:
> 
> ...
>
> Furthermore, after ___make allmodconfig && make bzImage modules___ this is the
> comparison of image and modules sizes:
> 
>     # Without this patch applied
>     $ ls -l arch/x86/boot/bzImage **/*.ko |awk '{size += $5} END {print size}'
>     350715800
> 
>     # With this patch applied
>     $ ls -l arch/x86/boot/bzImage **/*.ko |awk '{size += $5} END {print size}'
>     349856528

We saved nearly a megabyte by optimising min3(), max3() and clamp()? 

I'm counting a grand total of 182 callsites for those macros.  So the
saving is 4700 bytes per invokation?  I don't believe it...



  reply	other threads:[~2014-06-16 23:18 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-06-16 21:07 Michal Nazarewicz
2014-06-16 23:18 ` Andrew Morton [this message]
2014-06-16 23:25   ` David Rientjes
2014-06-16 23:35     ` Andrew Morton
2014-06-16 23:54       ` David Rientjes
2014-06-17  0:21         ` Steven Rostedt
2014-06-17  4:01           ` Steven Rostedt
2014-06-17 13:49   ` Michal Nazarewicz
2014-06-17 11:37 ` Hagen Paul Pfeifer

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