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Date: Tue, 22 Apr 2008 07:51:40 -0500
From: Eric Sandeen <sandeen@sandeen.net>
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To: Denys Vlasenko <vda.linux@googlemail.com>
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>,
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       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       Arjan van de Ven <arjan@infradead.org>,
       Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH] xfs: do not pass unused params to xfs_flush_pages
References: <20080419142329.GA5339@elte.hu> <200804220503.16888.vda.linux@googlemail.com> <480D586C.1030305@sandeen.net> <200804221057.33324.vda.linux@googlemail.com>
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Denys Vlasenko wrote:
> On Tuesday 22 April 2008 05:15, Eric Sandeen wrote:


>>> 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:

Sorry if you took it that way; since the patch was in response to Dave's
mention of accepting stack-reducing patches, I thought it was worth
checking and highlighting whether it seemed to help.  It wasn't supposed
to be an attack or argument.

> 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.

Hm, I had assumed that the %esp subtraction also made room for the
arguments pushed onto the stack.  Is there no way to analyze that part?

Thanks,
-Eric