linux-kernel - Re: [PATCH] xfs: do not pass unused params to xfs_flush

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Message-ID: <480DDF5C.6090808@sandeen.net>
Date:	Tue, 22 Apr 2008 07:51:40 -0500
From:	Eric Sandeen <sandeen@...deen.net>
To:	Denys Vlasenko <vda.linux@...glemail.com>
CC:	David Chinner <dgc@....com>, Adrian Bunk <bunk@...nel.org>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Shawn Bohrer <shawn.bohrer@...il.com>,
	Ingo Molnar <mingo@...e.hu>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Arjan van de Ven <arjan@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH] xfs: do not pass unused params to xfs_flush_pages

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
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