From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261967AbTLHUWi (ORCPT ); Mon, 8 Dec 2003 15:22:38 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262009AbTLHUWh (ORCPT ); Mon, 8 Dec 2003 15:22:37 -0500 Received: from holomorphy.com ([199.26.172.102]:47325 "EHLO holomorphy.com") by vger.kernel.org with ESMTP id S261967AbTLHUWg (ORCPT ); Mon, 8 Dec 2003 15:22:36 -0500 Date: Mon, 8 Dec 2003 12:22:29 -0800 From: William Lee Irwin III To: Per Andreas Buer Cc: linux-kernel@vger.kernel.org Subject: Re: 2.4: mylex and > 2GB RAM Message-ID: <20031208202229.GO8039@holomorphy.com> Mail-Followup-To: William Lee Irwin III , Per Andreas Buer , linux-kernel@vger.kernel.org References: <1070897058.25490.56.camel@netstat.linpro.no> <20031208153641.GJ8039@holomorphy.com> <1070898870.25490.76.camel@netstat.linpro.no> <20031208162214.GW19856@holomorphy.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Organization: The Domain of Holomorphy User-Agent: Mutt/1.5.4i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org William Lee Irwin III writes: >> If your memory ended at 2GB and the driver had 31-bit DMA, it may have >> decided to use unconstrained allocations. Then, when you added more RAM, >> it was forced to ask for <= 896MB, which made it copy to buffers that are >> actually below 896MB most of the time. On Mon, Dec 08, 2003 at 09:15:15PM +0100, Per Andreas Buer wrote: > But this would reduce the throuput only a few percent, right? My system > slows down from writing ~ 100MB/s to maybe 50KB/s. It could potentially slow it down a lot more than a few percent. The main effect you would see is heavy low memory consumption (LowFree: going down to almost nothing) and very heavy cpu consumption. -- wli