Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S264850AbUD2Uxx (ORCPT ); Thu, 29 Apr 2004 16:53:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264855AbUD2Uug (ORCPT ); Thu, 29 Apr 2004 16:50:36 -0400 Received: from mail.fastclick.com ([205.180.85.17]:52436 "EHLO mail.fastclick.net") by vger.kernel.org with ESMTP id S264781AbUD2UsX (ORCPT ); Thu, 29 Apr 2004 16:48:23 -0400 Message-ID: <409169F0.1020902@fastclick.com> Date: Thu, 29 Apr 2004 13:47:44 -0700 From: "Brett E." Reply-To: brettspamacct@fastclick.com User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.4) Gecko/20030624 X-Accept-Language: en-us, en MIME-Version: 1.0 To: William Lee Irwin III CC: Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: ~500 megs cached yet 2.6.5 goes into swap hell References: <409021D3.4060305@fastclick.com> <20040428170106.122fd94e.akpm@osdl.org> <40904FD8.7020208@fastclick.com> <20040428181319.601decfc.akpm@osdl.org> <40905A5E.5000807@fastclick.com> <409143F6.3050300@fastclick.com> <20040429183226.GA783@holomorphy.com> In-Reply-To: <20040429183226.GA783@holomorphy.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1735 Lines: 37 William Lee Irwin III wrote: > On Thu, Apr 29, 2004 at 11:05:42AM -0700, Brett E. wrote: > >>Anyone know what I should believe? Sar's pgpgin/s and pgpgout/s tell me >> that it is paging in/out from/to disk. Yet pswpin/s and pswpout/s are >>both 0. Swapping and paging are the same thing I believe. pgpgin/out >>refer to paging, pswpin/out refer to swapping. So I for one am confused. >>I guess I could dig through the source but I figured someone might have >>encountered this disrepency in the past. > > > Both are to be believed. They merely describe different things. > > Pagein/pageout are counts of VM-initiated IO, regardless of whether this > IO is done on filesystem-backed pages or swap-backed pages. Pagein and > pageout are used more generally to describe VM-initiated IO and don't > exclusively refer to swap IO, but also include IO to filesystems to/from > filesystem-backed memory. > > Swapin/swapout are counts of swap IO only, and are considered to apply > only to IO done to swap files/devices to/from swap-backed anonymous memory. > > Pagein/pageout are both proper and necessary to have. In fact, you were > requesting that filesystem IO be done preferentially to swap IO, and the > pagein/pageout indicators showing IO while swapin/swapout indicators show > none mean you are getting exactly what you asked for. > > Thanks I think it's clear now. In layman's terms, pgpgin/out relate to disk cache activity vs pswpin/out which relate to swap activity. - 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/