From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265586AbUEZNCp (ORCPT ); Wed, 26 May 2004 09:02:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S265588AbUEZNAi (ORCPT ); Wed, 26 May 2004 09:00:38 -0400 Received: from rwcrmhc11.comcast.net ([204.127.198.35]:7350 "EHLO rwcrmhc11.comcast.net") by vger.kernel.org with ESMTP id S265582AbUEZNAL (ORCPT ); Wed, 26 May 2004 09:00:11 -0400 From: "Buddy Lumpkin" To: "'Nick Piggin'" Cc: "'John Bradford'" , "'William Lee Irwin III'" , , Subject: RE: why swap at all? Date: Wed, 26 May 2004 06:03:02 -0700 MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Mailer: Microsoft Office Outlook, Build 11.0.5510 In-Reply-To: <40B48C78.6040005@yahoo.com.au> X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1409 Thread-Index: AcRDHMqToSOQGm/VSjiKdHxE/58ETQABB0jw Message-Id: Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org >> Couple that with the fact that there are many pte's pointing at the same >> physical page (shared page) in many cases where many processes >> >> are running >> on the system. Because all of the references to that page must be removed >> before the page can be evicted, there are some absolute >> limitations in the >> rate that pages can be evicted from memory as the number of processes >> running on the system and the total amount of memory increases. >> > This is still many orders of magnitude faster than filling the page > from disk, and you typically don't reclaim much of mapped memory anyway. This discussion went broke-minded again. Your still picturing that single IDE hard drive in your workstation and im talking about big iron, large databases, etc.. where the total amount of aggregate disk I/O is completely limited by the rate you can evict pages from the pagecache. Picture 6 to 7 fibre channel cards with over 70% utilization during peak usage times connected to a large EMC storage array with 64GB of non-volatile cache. --Buddy