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From: Eric Sandeen <sandeen@redhat.com>
To: Andi Kleen <andi@firstfloor.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	linux-kernel@vger.kernel.org, rth@redhat.com
Subject: Re: [PATCH] reduce large do_mount stack usage with noinlines
Date: Fri, 08 Feb 2008 10:54:09 -0600	[thread overview]
Message-ID: <47AC8931.50704@redhat.com> (raw)
In-Reply-To: <p73myqb2y09.fsf@bingen.suse.de>

Andi Kleen wrote:
> Andrew Morton <akpm@linux-foundation.org> writes:
>>>   */
>>> -static int do_change_type(struct nameidata *nd, int flag)
>>> +static noinline int do_change_type(struct nameidata *nd, int flag)
>> What we could do here is defined a new noinline_because_of_stack_suckiness
>> and use that.  Reasons:
>>
>> - self-documenting, so we don't need to comment each site
>>
>> - can be made a no-op for suitable __GNUC__ values if gcc ever fixes this
> 
> In theory it should be already fixed; iirc Richard H. (cc'ed) added
> code for this somewhere in 4.x. Don't quite remember which x, likely 
> either 1 or 2.
> 
> e.g. if I do a quick test here on gcc 4.2 then it definitely
> reuses stack slots between inlines. As you can see only ~100 bytes
> are allocated, not ~200.

On gcc 4.1.2 and 4.3 (fedora flavors) I don't see it re-used in
do_mount, though... *shrug*

-Eric

  reply	other threads:[~2008-02-08 17:06 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
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 [this message]
2008-02-08 17:23           ` Al Viro

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