linux-kernel - Re: [PATCH 0/3] ARM 4Kstacks: introduction

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Message-ID: <CACVXFVMb9p8PiTYWGTNn-FtQts0sRgmK+BQ6kaJ6-D89CAT=xQ@mail.gmail.com>
Date:	Sat, 22 Oct 2011 16:50:15 +0800
From:	Ming Lei <tom.leiming@...il.com>
To:	Arnd Bergmann <arnd@...db.de>
Cc:	linux-arm-kernel@...ts.infradead.org,
	Tim Bird <tim.bird@...sony.com>, Joe Perches <joe@...ches.com>,
	linux kernel <linux-kernel@...r.kernel.org>,
	Andi Kleen <andi@...stfloor.org>,
	Russell King <rmk@....linux.org.uk>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 0/3] ARM 4Kstacks: introduction

On Wed, Oct 19, 2011 at 6:51 PM, Arnd Bergmann <arnd@...db.de> wrote:
> On Tuesday 18 October 2011 17:26:44 Tim Bird wrote:
>> Even inside Sony, usage of 4K stacks is limited
>> to some very special cases, where memory is exceedingly
>> tight (we have one system with 4M of RAM).  And we
>> don't mind lopping off features or coding around
>> problem areas to support our special case.
>
> I would imagine that in those cases, you can gain more by reducing the
> number of threads in the system. What is the highest number of
> concurrent threads that you expect in a limited use case with no
> networking or block devices?

If system run for some time, sometimes it may be difficult for
memory allocator to allocate 2 continuous page frames even  there are
many spare page frames in system because of
fragment issue, so the patch does make sense. Anyway,
it provides one option for user to apply 4k stack to avoid
such kind of process creation failure.

thanks,
-- 
Ming Lei
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