linux-kernel - Re: x86: 4kstacks default

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Date:	Sun, 20 Apr 2008 22:23:45 +0200
From:	Bodo Eggert <7eggert@....de>
To:	Daniel Hazelton <dhazelton@...er.net>,
	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>,
	Andi Kleen <andi@...stfloor.org>
Subject: Re: x86: 4kstacks default

Daniel Hazelton <dhazelton@...er.net> wrote:
> On Sunday 20 April 2008 08:27:14 Andi Kleen wrote:
>> Adrian Bunk <bunk@...nel.org> writes:
>> > 6k is known to work, and there aren't many problems known with 4k.
>> >
>> > And from a QA point of view the only way of getting 4k thoroughly tested
>>
>> But you have to first ask why do you want 4k tested? Does it serve
>> any useful purpose in itself? I don't think so. Or you're saying
>> it's important to support 50k kernel threads on 32bit kernels?

> Andi, you're the only one I've seen seriously pounding the "50k threads"
> thing - I don't think anyone is really fooled by the straw-man, so I'd
> suggest you drop it.
> 
> The real issue is that you think (and are correct in thinking) that people are
> idiots. Yes, there will be breakages if the default is changed to 4k stacks -
> but if people are running new kernels on boxes that'll hit stack use problems
> (that *AREN'T* related to ndiswrapper) and haven't made sure that they've
> configured the kernel properly, then they deserve the outcome. It isn't the
> job of the Linux Kernel to protect the incompetent - nor is it the job of
> linux kernel developers to do such.

It's the job of the kernel developers to mark experimental and broken options,
and to put a warning:

"This will break stacking of drivers, especially if disk manager, xfs, RAID
and nfs are used. Yes, linux is broken by default, but only if you intend to
set up a reliable system, so this will be OK!"

into the help text, instead of expecting each admin to read lkml.

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