From owner-freebsd-security Wed Aug 11 13:52:10 1999 Delivered-To: freebsd-security@freebsd.org Received: from apollo.backplane.com (apollo.backplane.com [209.157.86.2]) by hub.freebsd.org (Postfix) with ESMTP id C1F1314BFE for ; Wed, 11 Aug 1999 13:52:07 -0700 (PDT) (envelope-from dillon@apollo.backplane.com) Received: (from dillon@localhost) by apollo.backplane.com (8.9.3/8.9.1) id NAA77694; Wed, 11 Aug 1999 13:51:58 -0700 (PDT) (envelope-from dillon) Date: Wed, 11 Aug 1999 13:51:58 -0700 (PDT) From: Matthew Dillon Message-Id: <199908112051.NAA77694@apollo.backplane.com> To: John-Mark Gurney Cc: Jeff Aitken , des@flood.ping.uio.no, freebsd-security@FreeBSD.ORG Subject: Re: 4 Swap partitions limit (was Re: RE: Little question (offtopic)) References: <14257.50009.162402.381699@trooper.velocet.ca> <199908111851.OAA21052@eagle.aitken.com> <19990811120248.23702@hydrogen.fircrest.net> Sender: owner-freebsd-security@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org :this should also be updated to say that it doesn't dump and zero the :pages... it just puts them on disk so if there is an immediate need :for a large chunk of memory that it can dump pages that have been swapped :out w/o having to wait for them to be swapped out.. : :so the more use of swap actually helps performance because you can get :large chunks of memory faster... : :-- : John-Mark Gurney Voice: +1 541 684 8449 : Cu Networking P.O. Box 5693, 97405 Most systems work this way. You have dirty pages, clean pages, and free pages. The act of allocating swap and writing a dirty page to the swap block simply changes the page from dirty to clean and does not remove it. If the page is touched again prior to being reused, the underlying swap allocation is simply thrown away. If the page is accessed prior to being reused its LRU position is reset but the swap remains allocated. If the page is reused and then later touched or accessed, the page is loaded in from its swap backing store and (if the page is being touched), the swap backing store is deallocated. -Matt To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-security" in the body of the message