From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S264825AbUEKQZr (ORCPT ); Tue, 11 May 2004 12:25:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264826AbUEKQZr (ORCPT ); Tue, 11 May 2004 12:25:47 -0400 Received: from mtvcafw.SGI.COM ([192.48.171.6]:27627 "EHLO omx3.sgi.com") by vger.kernel.org with ESMTP id S264825AbUEKQZI (ORCPT ); Tue, 11 May 2004 12:25:08 -0400 Message-ID: <40A0FF29.1060006@sgi.com> Date: Tue, 11 May 2004 11:28:25 -0500 From: Ray Bryant User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.4) Gecko/20030624 Netscape/7.1 X-Accept-Language: en-us, en MIME-Version: 1.0 To: John Bradford CC: Silviu Marin-Caea , linux-kernel@vger.kernel.org Subject: Re: dynamic allocation of swap disk space References: <40A0EFC0.1040609@sgi.com> <200405111552.i4BFqFMN000112@81-2-122-30.bradfords.org.uk> In-Reply-To: <200405111552.i4BFqFMN000112@81-2-122-30.bradfords.org.uk> 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 Hi John, John Bradford wrote: > > > Not necessarily. Increasing swap can allow more physical RAM to be used for > caching data from disk. > > Imagine a system with limited physical RAM, and limited swap space, running a > process which causes a lot of filesystem activity on the same physical disk > as is being used for swap. If the total RAM, both physical and swap is almost > completely full, increasing the swap space may allow some data from physical > RAM to be swapped out, in favour of caching filesystem data from the disk. Hmmm... Lets see, we have a program (or set of programs) in memory that is thrashing, i. e. it is page faulting at a rate that is higher than the vm system can supply pages, so it is spending its time waiting for pages and the disk subsystem is busy. Now, if we increase the amount of data cached from disk, without increasing main memory, we've decreased the amount of memory available to the thrashing program, perhaps making its problems worse? Well, I guess all this shows is that with the vm subsystem, speculation is often useless, one has to fire up the box with a carefully constructed workload and see what happens. > > Without knowing more details of the original poster's machine, it's difficult > to give specific advice about how to solve the problem. > I certainly agree with that. Time for this thread to die, I think. :-) Cheers. > John. > -- Best Regards, Ray ----------------------------------------------- Ray Bryant 512-453-9679 (work) 512-507-7807 (cell) raybry@sgi.com raybry@austin.rr.com The box said: "Requires Windows 98 or better", so I installed Linux. -----------------------------------------------