Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933125AbXF2FYy (ORCPT ); Fri, 29 Jun 2007 01:24:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751640AbXF2FYp (ORCPT ); Fri, 29 Jun 2007 01:24:45 -0400 Received: from smtp2.linux-foundation.org ([207.189.120.14]:44596 "EHLO smtp2.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751196AbXF2FYo (ORCPT ); Fri, 29 Jun 2007 01:24:44 -0400 Date: Thu, 28 Jun 2007 22:24:24 -0700 From: Andrew Morton To: David Miller Cc: clameter@sgi.com, hugh@veritas.com, James.Bottomley@steeleye.com, rmk+lkml@arm.linux.org.uk, linux-kernel@vger.kernel.org Subject: Re: [PATCH] Containment measures for slab objects on scatter gather lists Message-Id: <20070628222424.4cbae90c.akpm@linux-foundation.org> In-Reply-To: <20070628.220606.112621271.davem@davemloft.net> References: <20070628.212825.78710369.davem@davemloft.net> <20070628.220606.112621271.davem@davemloft.net> X-Mailer: Sylpheed 2.4.1 (GTK+ 2.8.17; x86_64-unknown-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1388 Lines: 35 On Thu, 28 Jun 2007 22:06:06 -0700 (PDT) David Miller wrote: > From: Christoph Lameter > Date: Thu, 28 Jun 2007 21:39:01 -0700 (PDT) > > > Hmmmm... Maybe we are creating more of a mess with this. Isnt there some > > other way to handle these object. > > That's where I was going with the silly idea to use another > allocator :) > > Really, it would be great if we could treat kmalloc() objects > just like real pages. >From a high level, that seems like a bad idea. kmalloc() gives you a virtual address and you really shouldn't be poking around at that memory's underlying page's pageframe metadata. However we can of course do tasteless and weird things if the benefit is sufficient.... > Everything wants to do I/O on pages > but sometimes (like the networking) you have a kmalloc > chunk which is technically just a part of a page. hm. So what happens when two quite different threads of control are doing IO against two hunks of kmalloced memory which happen to come from the same page? Either some (kernel-wide) locking is needed, or that pageframe needs to be treated as readonly? - 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/