linux-kernel - Re: 4KSTACKS + DEBUG

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Message-Id: <200708311211.25143.vda.linux@googlemail.com>
Date:	Fri, 31 Aug 2007 12:11:25 +0100
From:	Denys Vlasenko <vda.linux@...glemail.com>
To:	Eric Sandeen <sandeen@...hat.com>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Jesper Juhl <jesper.juhl@...il.com>
Subject: Re: 4KSTACKS + DEBUG_STACKOVERFLOW harmful

On Wednesday 29 August 2007 23:34, Eric Sandeen wrote:
> Noticed today that the combination of 4KSTACKS and DEBUG_STACKOVERFLOW
> config options is a bit deadly.
>
> DEBUG_STACKOVERFLOW warns in do_IRQ if we're within THREAD_SIZE/8 of the
> end of useable stack space, or 512 bytes on a 4k stack.
...
> The large stack usage in those 2 functions is due to big char arrays, of
> size KSYM_NAME_LEN (128 bytes) and KSYM_SYMBOL_LEN (223 bytes).
>
> IOW, the stack warning effectively reduces useful stack left in our itty
> bitty 4k stacks by over 10%.

KSYM_NAME_LEN = 128 sounds stupid. The name which is wider than 80 chars??
Kernel shouldn't have names that long.
Say, 50 chars ought to be enough.
--
vda
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