From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263195AbTEGNog (ORCPT ); Wed, 7 May 2003 09:44:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263199AbTEGNog (ORCPT ); Wed, 7 May 2003 09:44:36 -0400 Received: from wohnheim.fh-wedel.de ([195.37.86.122]:36043 "EHLO wohnheim.fh-wedel.de") by vger.kernel.org with ESMTP id S263195AbTEGNof (ORCPT ); Wed, 7 May 2003 09:44:35 -0400 Date: Wed, 7 May 2003 15:56:57 +0200 From: =?iso-8859-1?Q?J=F6rn?= Engel To: "Richard B. Johnson" Cc: Linux kernel Subject: Re: top stack (l)users for 2.5.69 Message-ID: <20030507135657.GC18177@wohnheim.fh-wedel.de> References: <20030507132024.GB18177@wohnheim.fh-wedel.de> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.3.28i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 7 May 2003 09:45:13 -0400, Richard B. Johnson wrote: > > You know (I hope) that allocating stuff on the stack is not > "bad". In fact, it's the quickest way to allocate data that > will automatically go away when the function returns. One > just subtracts a value from the stack-pointer and you have > the data area. I sure hope that these temporary allocations > are not being replaced with kmalloc()/kfree(). If so, the > code is badly broken and you are eating my CPU cycles for > nothing. Agreed, partially. There is the current issue of the kernel stack being just 8k in size and no decent mechanism in place to detect a stack overflow. And there is (arguably) the future issue of the kernel stack shrinking to 4k. Stuff like intermezzo will break with 4k, no discussion about that. Other stuff may or may not work. What I'm trying to do is pave the way to shrink the kernel stack during 2.7 sometime. If there is large agreement that the kernel stack should not shrink, I'll stop this effort any day. But so far, I am under the impression that the agreement is to do the shink. Am I wrong? Jörn -- Time? What's that? Time is only worth what you do with it. -- Theo de Raadt