From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758494AbYDUDa0 (ORCPT ); Sun, 20 Apr 2008 23:30:26 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754521AbYDUDaM (ORCPT ); Sun, 20 Apr 2008 23:30:12 -0400 Received: from ug-out-1314.google.com ([66.249.92.169]:16931 "EHLO ug-out-1314.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754430AbYDUDaL (ORCPT ); Sun, 20 Apr 2008 23:30:11 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:user-agent:mime-version:to:cc:subject:references:in-reply-to:content-type:content-transfer-encoding; b=WIzL0HOLQQ3mwggQZvnJ6O98N+FsQZFy0hXAB8zrhvpObaDXEOAcSh7qJlAzWMTfxrNgXEmKhUUEI1bK+bJlTMPzHo439F5rLPRZqJRn14I+Fl4PfO12gNF+Bq37ix5qzJGh0UT/R4JLn3P5hBLCl4GXotMP3AmsEgIoalzjhiw= Message-ID: <480C0A39.7080501@gmail.com> Date: Mon, 21 Apr 2008 09:30:01 +0600 From: "Alexander E. Patrakov" User-Agent: Mozilla/5.0 (X11; U; Linux i686; ru-RU; rv:1.8.1.12) Gecko/20080129 Iceape/1.1.8 (Debian-1.1.8-2) Mnenhy/0.7.5.666 MIME-Version: 1.0 To: Adrian Bunk CC: Arjan van de Ven , Eric Sandeen , Alan Cox , Shawn Bohrer , Ingo Molnar , Andrew Morton , Linux Kernel Mailing List , Thomas Gleixner Subject: Re: x86: 4kstacks default References: <20080420090623.7b173ef1@the-village.bc.nu> <20080420085104.GG1595@cs181133002.pp.htv.fi> <20080420103611.2c0d3519@the-village.bc.nu> <20080420104444.GI1595@cs181133002.pp.htv.fi> <20080420120250.4f496861@the-village.bc.nu> <20080420115455.GJ1595@cs181133002.pp.htv.fi> <20080420123731.7282bb16@the-village.bc.nu> <20080420121803.GK1595@cs181133002.pp.htv.fi> <480B4DB4.8070107@sandeen.net> <20080420084127.2fc324ec@laptopd505.fenrus.org> <20080420160327.GE1899@cs181133002.pp.htv.fi> In-Reply-To: <20080420160327.GE1899@cs181133002.pp.htv.fi> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Adrian Bunk wrote: > On Sun, Apr 20, 2008 at 08:41:27AM -0700, Arjan van de Ven wrote: >> ... >> yes. Adrian is waay off in the weeds on this one. Nobody but him is suggesting to remove >> 8Kb stacks. I think everyone else agrees that having both options is valuable; and there >> are better ways to find+fix stack bloat than removing this config option. > > I'm not arguing for removing the option immediately, but long-term we > shouldn't need it. > > This comes from my experience of removing obsolete drivers for hardware > for which also a more recent driver exists: > As long as there is some workaround (e.g. using an older driver or > 8k stacks) the workaround will be used instead of the getting proper > bug reports and fixes. > > As far as I know all problems that are known with 4k stacks are some > nested things with XFS in the trace. This "as far as I know" is a problem itself. Is it possible to implement (e.g., using some form of memory protection in hardware, but I am not an expert here) an option with 8k stacks that, however, spams the log if the actual usage goes above 4k, and have this as a default for some time? If 4k stacks are the goal that is almost achieved, then this debugging option should have zero impact on performance. -- Alexander E. Patrakov