From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 20 Aug 2001 18:48:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 20 Aug 2001 18:48:16 -0400 Received: from humbolt.nl.linux.org ([131.211.28.48]:15876 "EHLO humbolt.nl.linux.org") by vger.kernel.org with ESMTP id ; Mon, 20 Aug 2001 18:47:58 -0400 Content-Type: text/plain; charset=US-ASCII From: Daniel Phillips To: Marcelo Tosatti Subject: Re: 2.4.8/2.4.9 VM problems Date: Tue, 21 Aug 2001 00:54:32 +0200 X-Mailer: KMail [version 1.3.1] Cc: Mike Galbraith , Frank Dekervel , linux-kernel@vger.kernel.org In-Reply-To: In-Reply-To: MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Message-Id: <20010820224802Z16009-32384+228@humbolt.nl.linux.org> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On August 20, 2001 10:16 pm, Marcelo Tosatti wrote: > On Mon, 20 Aug 2001, Marcelo Tosatti wrote: > > On Mon, 20 Aug 2001, Daniel Phillips wrote: > > > On Mon, 20 Aug 2001, Marcelo Tosatti wrote: > > > > Find riel's message with topic "VM tuning" to linux-mm, then take a look > > > > at the 4th aging option. > > > > > > > > That one _should_ be able to make us remove all kinds of "hacks" to do > > > > drop behind, and also it should keep hot/warm active memory _in cache_ > > > > for more time. > > > > > > I looked at it yesterday. The problem is, it loses the information about *how* > > > a page is used: pagecache lookup via readahead has different implications than > > > actual usage. > > And ah, I forgot something here. > > Your statement which says "pagecache lookup via readahead has different > implications than actual usage" is not really correct. > > If you only consider "hot" pages as "pages which have been touched", > you're going to (potentially) fuck heavy streaming IO workloads. "Hot" pages are pages that have been touched more than once. The idea of use-once (on the read side) is to retain the readahead pages just long enough to use them, and not a lot longer. If you've seen streaming IO pages getting evicted before being used, I'd like to know about it because something is broken in that case. -- Daniel