From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759255AbYGOUuO (ORCPT ); Tue, 15 Jul 2008 16:50:14 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1763658AbYGOUtp (ORCPT ); Tue, 15 Jul 2008 16:49:45 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:56683 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1763095AbYGOUto (ORCPT ); Tue, 15 Jul 2008 16:49:44 -0400 Date: Tue, 15 Jul 2008 13:48:48 -0700 From: Andrew Morton To: Rik van Riel Cc: linux-kernel@vger.kernel.org, Lee.Schermerhorn@hp.com, kosaki.motohiro@jp.fujitsu.com Subject: Re: [PATCH][RFC] evict streaming IO cache first Message-Id: <20080715134848.cf2204b9.akpm@linux-foundation.org> In-Reply-To: <20080715160948.097b14a4@cuia.bos.redhat.com> References: <20080715160948.097b14a4@cuia.bos.redhat.com> X-Mailer: Sylpheed version 2.2.4 (GTK+ 2.8.20; i486-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 15 Jul 2008 16:09:48 -0400 Rik van Riel wrote: > This patch still needs some testing under various workloads > on different hardware - the approach should work but the > threshold may need tweaking. > More than "some"! > > When there is a lot of streaming IO going on, we do not want > to scan or evict pages from the working set. The old VM used > to skip any mapped page, but still evict indirect blocks and > other data that is useful to cache. I'd be surprised if indirect blocks are getting kicked - they tend to be awfully sticky due to frequent touch_buffer()s or equivalent. inode blocks tend to be pretty sticky too - this is affected a lot by whether or not atime updates are enabled. directory blocks might be less sticky, but that might be what we want to happen. > This patch adds logic to skip scanning the anon lists and > the active file list if most of the file pages are on the > inactive file list (where streaming IO pages live), while > at the lowest scanning priority. > > If the system is not doing a lot of streaming IO, eg. the > system is running a database workload, then more often used > file pages will be on the active file list and this logic > is automatically disabled. >