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From: Denys Vlasenko <vda.linux@googlemail.com>
To: Eric Sandeen <sandeen@sandeen.net>
Subject: Re: [PATCH] xfs: do not pass unused params to xfs_flush_pages
Date: Tue, 22 Apr 2008 10:57:33 +0200
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Cc: David Chinner <dgc@sgi.com>, Adrian Bunk <bunk@kernel.org>,
       Alan Cox <alan@lxorguk.ukuu.org.uk>,
       Shawn Bohrer <shawn.bohrer@gmail.com>, Ingo Molnar <mingo@elte.hu>,
       Andrew Morton <akpm@linux-foundation.org>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       Arjan van de Ven <arjan@infradead.org>,
       Thomas Gleixner <tglx@linutronix.de>
References: <20080419142329.GA5339@elte.hu> <200804220503.16888.vda.linux@googlemail.com> <480D586C.1030305@sandeen.net>
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On Tuesday 22 April 2008 05:15, Eric Sandeen wrote:
> Denys Vlasenko wrote:
> > Hi David,
> > 
> > xfs_flush_pages() does not use some of its parameters, namely:
> > first, last and fiops.
> > 
> > This patch removes these parameters from all callsites.
> > 
> > Code size difference on 32-bit x86:
> > 
> >    text    data     bss     dec     hex filename
> >  390739    2748    1708  395195   607bb linux-2.6-xfs1-TEST/fs/xfs/xfs.o
> >  390567    2748    1708  395023   6070f linux-2.6-xfs2-TEST/fs/xfs/xfs.o
> > 
> > Compile-tested only.
> 
> FWIW this one actually does not seem to reduce stack usage anywhere.

I hope this will not deteriorate into a contest whether
every particular patch reduces stack usage or not, but:

You do not see reduced stack usage in "make checkstack",
because "make checkstack" shows only stack usage caused by
local variables (it analyses sub %esp,NN instructions which
make room for them). Parameters also take up stack, but
they are pushed on stack with push instruction,
and so are invisible in "make checkstack" output.
--
vda