Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 19 Nov 2001 05:52:16 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 19 Nov 2001 05:52:06 -0500 Received: from mta.sara.nl ([145.100.16.144]:15255 "EHLO mta.sara.nl") by vger.kernel.org with ESMTP id convert rfc822-to-8bit; Mon, 19 Nov 2001 05:51:56 -0500 Message-Id: <200111191051.LAA04099@zhadum.sara.nl> X-Mailer: exmh version 2.1.1 10/15/1999 From: Remco Post To: linux-kernel@vger.kernel.org Subject: Re: Swap In-Reply-To: Message from James A Sutherland of "Mon, 19 Nov 2001 09:18:11 GMT." Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Mime-Version: 1.0 Content-Transfer-Encoding: 7BIT Date: Mon, 19 Nov 2001 11:51:44 +0100 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org --8<-- > Except that openoffice and mozilla can be swapped out in BOTH cases: the > kernel can discard mapped pages and reread as needed, whether you have a swap > partition or not. > No they can't without swap, nothing can be SWAPPED out. The code pages can be paged out (discarded), but no SWAPPING takes place. > Whereas without swapspace, only the read-only mapped pages can be swapped out. Again, pages do not gat swapped out, only applications can get swapped out. Swapping is per definition the process of removing all pages used by one application from RAM, and moving ALL pages to swap. > Provided the VM is doing its job properly, adding swap will always be a net > win for efficiency: the kernel is able to dump unused pages to make more room > for others. Of course, you tend to "feel" the response times to interactive > events, rather than the overall throughput, so a change which slows the > system down but makes it more "responsive" to mouse clicks etc feels like a > net win... > > > James. With any properly sized system, it will NEVER SWAP. Paging is a completely different thing. A little paging is not a problem. Up to 70 pagescans/s on occasion is quite acceptable. If paging activety grows above that, you may have a real problem. I don't know about the current VM, but with most unixes when you hit this mark, the system actually starts swapping, and your responsiveness goes down the drain.... -- Met vriendelijke groeten, Remco Post SARA - Stichting Academisch Rekencentrum Amsterdam High Performance Computing Tel. +31 20 592 8008 Fax. +31 20 668 3167 "I really didn't foresee the Internet. But then, neither did the computer industry. Not that that tells us very much of course - the computer industry didn't even foresee that the century was going to end." -- Douglas Adams - 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/