Message-ID: <43ABD178.2020203@cosmosbay.com>
Date: Fri, 23 Dec 2005 11:29:12 +0100
From: Eric Dumazet <dada1@cosmosbay.com>
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To: 7eggert@gmx.de
CC: Horst von Brand <vonbrand@inf.utfsm.cl>,
       Parag Warudkar <kernel-stuff@comcast.net>,
       Dumitru Ciobarcianu <Dumitru.Ciobarcianu@iNES.RO>,
       Helge Hafting <helge.hafting@aitel.hist.no>, Andi Kleen <ak@suse.de>,
       Adrian Bunk <bunk@stusta.de>, Kyle Moffett <mrmacman_g4@mac.com>,
       akpm@osdl.org, linux-kernel@vger.kernel.org, arjan@infradead.org
Subject: Re: [2.6 patch] i386: always use 4k stacks
References: <5lQOU-492-31@gated-at.bofh.it> <5lQOU-492-29@gated-at.bofh.it> <E1Epjug-0001iA-In@be1.lrz>
In-Reply-To: <E1Epjug-0001iA-In@be1.lrz>
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Bodo Eggert a ?crit :
> Horst von Brand <vonbrand@inf.utfsm.cl> wrote:
> 
>> "With some drawbacks" is the point: It has been determined that the
>> drawbacks are heavy enough that the 8KiB stack option should go.
> 
> Determined by voodoo and wild guessing.
> 
> Let's detect the need for 4K stacks: (I hope I found the correct place)
> 
> (Maybe the printk should be completely ifdefed, but I'm not sure)
> 
> 
> Signed-off-by: Bodo Eggert <7eggert@gmx.de>
> 
> --- 2.6.14/kernel/fork.c.ori    2005-12-21 19:06:24.000000000 +0100
> +++ 2.6.14/kernel/fork.c        2005-12-21 19:15:23.000000000 +0100
> @@ -168,4 +168,9 @@ static struct task_struct *dup_task_stru
>         if (!ti) {
>                 free_task_struct(tsk);
> +               printk(KERN_WARNING, "Can't allocate new task structure"
> +#ifndef CONFIG_4KSTACKS
> +               ". Maybe you could benefit from 4K stacks.\n"
> +#endif
> +               "\n");
>                 return NULL;
>         }
> 

This patch is not OK but for i386 architecture.

For example, x86_64 cannot use a 4K stack, it needs a 8KB stack (so a order-1 
allocation that may fail)

Eric

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