Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753738AbYH0AYW (ORCPT ); Tue, 26 Aug 2008 20:24:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752366AbYH0AYI (ORCPT ); Tue, 26 Aug 2008 20:24:08 -0400 Received: from smtp5.pp.htv.fi ([213.243.153.39]:42825 "EHLO smtp5.pp.htv.fi" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752207AbYH0AYG (ORCPT ); Tue, 26 Aug 2008 20:24:06 -0400 Date: Wed, 27 Aug 2008 03:23:16 +0300 From: Adrian Bunk To: Linus Torvalds Cc: Rusty Russell , "Alan D. Brunelle" , "Rafael J. Wysocki" , Linux Kernel Mailing List , Kernel Testers List , Andrew Morton , Arjan van de Ven , Ingo Molnar , linux-embedded@vger.kernel.org Subject: Re: [Bug #11342] Linux 2.6.27-rc3: kernel BUG at mm/vmalloc.c - bisected Message-ID: <20080827002316.GE11734@cs181140183.pp.htv.fi> References: <48B313E0.1000501@hp.com> <200808261111.19205.rusty@rustcorp.com.au> <20080826183051.GB10925@cs181140183.pp.htv.fi> <20080826205916.GB11734@cs181140183.pp.htv.fi> <20080826232411.GC11734@cs181140183.pp.htv.fi> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2008 Lines: 76 On Tue, Aug 26, 2008 at 04:51:52PM -0700, Linus Torvalds wrote: > > > On Wed, 27 Aug 2008, Adrian Bunk wrote: > > > > > > We're much better off with a 1% code-size reduction than forcing big > > > stacks on people. The 4kB stack option is also a good way of saying "if it > > > works with this, then 8kB is certainly safe". > > > > You implicitely assume both would solve the same problem. > > I'm just saying that your logic doesn't hold water. > > If we can save kernel stack usage, then a 1% increase in kernel size is > more than worth it. >From some tests the size increase seems to become bigger for smaller kernels, but I don't have any really good data. An interesting question is why most of our architectures for embedded devices only offer bigger stacks: The only architectures offering a 4kB stacks option are: - m68knommu - sh - 32bit x86 The following architectures that are used in embedded devices always use 8kB stacks (or bigger) in your tree: - arm - avr32 - blackfin - cris - frv - h8300 - m32r - m68k - mips - mn10300 (has an #ifdef CONFIG_4KSTACKS but no kconfig option) - powerpc - xtensa > > While 4kB stacks are something we anyway never got 100% working > > What? Don't be silly. > > Linux _historically_ always used 4kB stacks. > > No, they are likely not usable on x86-64, but dammit, they should be more > than usable on x86-32 still. When did we get callpaths like like nfs+xfs+md+scsi reliably working with 4kB stacks on x86-32? >... > Linus cu Adrian -- "Is there not promise of rain?" Ling Tan asked suddenly out of the darkness. There had been need of rain for many days. "Only a promise," Lao Er said. Pearl S. Buck - Dragon Seed -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/