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From: Arjan van de Ven <arjan@infradead.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Eric Sandeen <sandeen@redhat.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] reduce large do_mount stack usage with noinlines
Date: Wed, 6 Feb 2008 14:54:39 -0800	[thread overview]
Message-ID: <20080206145439.4ef971f2@laptopd505.fenrus.org> (raw)
In-Reply-To: <20080206143457.03e8741d.akpm@linux-foundation.org>

On Wed, 6 Feb 2008 14:34:57 -0800
Andrew Morton <akpm@linux-foundation.org> wrote:

> 
> Does the patch actually help?  I mean, if a() calls b() and both use N
> bytes of locals, our worst-case stack usage remains ~2N whether or
> not b() was inlined in a()?  In fact, uninlining makes things a
> little worse due to callframe stuff.

it gets interesting at the three-way..
if a() calls b() and then calls c(), and they all use N,
the total usage is now 3N not 2N.

(although current gcc is already somewhat smarter about this, and 3N might actually be 2N for some cases)

  reply	other threads:[~2008-02-06 22:55 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-06 22:13 Eric Sandeen
2008-02-06 22:34 ` Andrew Morton
2008-02-06 22:54   ` Arjan van de Ven [this message]
2008-02-06 23:01     ` Eric Sandeen
2008-02-06 22:55   ` Eric Sandeen
2008-02-06 23:11   ` Eric Sandeen
2008-02-06 23:22     ` Andrew Morton
2008-02-06 23:34       ` Eric Sandeen
2008-02-06 23:46         ` Andrew Morton
2008-02-07 23:08       ` Eric Sandeen
2008-02-07 23:23         ` Arjan van de Ven
2008-02-07 23:26         ` Andrew Morton
2008-02-08 16:50       ` Andi Kleen
2008-02-08 16:54         ` Eric Sandeen
2008-02-08 17:23           ` Al Viro

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