From owner-freebsd-questions@FreeBSD.ORG Tue Jun 21 13:30:29 2005 Return-Path: X-Original-To: questions@freebsd.org Delivered-To: freebsd-questions@FreeBSD.ORG Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 89AF716A41F for ; Tue, 21 Jun 2005 13:30:29 +0000 (GMT) (envelope-from wmoran@potentialtech.com) Received: from internet.potentialtech.com (internet.potentialtech.com [66.167.251.6]) by mx1.FreeBSD.org (Postfix) with ESMTP id 56DFE43D55 for ; Tue, 21 Jun 2005 13:30:29 +0000 (GMT) (envelope-from wmoran@potentialtech.com) Received: from localhost (24-53-250-148.pittpa.adelphia.net [24.53.250.148]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by internet.potentialtech.com (Postfix) with ESMTP id 7262869A22; Tue, 21 Jun 2005 09:30:28 -0400 (EDT) Date: Tue, 21 Jun 2005 09:30:27 -0400 From: Bill Moran To: Francisco Reyes Message-Id: <20050621093027.24d339fa.wmoran@potentialtech.com> In-Reply-To: <20050620225204.F41158@zoraida.natserv.net> References: <20050620141439.S36309@zoraida.natserv.net> <20050620182430.GE8497@dan.emsphone.com> <20050620144631.F37558@zoraida.natserv.net> <20050620185545.GF8497@dan.emsphone.com> <20050620225204.F41158@zoraida.natserv.net> Organization: Potential Technologies X-Mailer: Sylpheed version 1.0.4 (GTK+ 1.2.10; i386-portbld-freebsd5.3) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: questions@freebsd.org, dnelson@allantgroup.com Subject: Re: When does swap decreases X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 21 Jun 2005 13:30:29 -0000 Francisco Reyes wrote: > On Mon, 20 Jun 2005, Dan Nelson wrote: > > When the system is low on memory, it will force the least used > > blocks of memory to swap. It will not free the swap space until > > the process owning them exits > > Have not found any program to see what programs are using the swap, but as > I think about it, the current method is not very "smart". I guess any > other method is difficult to implement. > > How wonder how the current method affects performance. > Basically if there is a surge of memory usage and processes start that use > the swap and these processes are long lived.. I wonder if performance > will be affected. The answer that was given to you on the usage of swap is greatly simplified. As a result, it's natural that you would ask these kinds of questions. In reality, FreeBSD's use of swap is _highly_ optimized. Even if you don't fully understand what it's doing ;) If you're interested in the nitty-gritty details, I suggest you purchase (or borrow) a copy of _The_Design_and_Implementation_of_FreeBSD_ and read the detailed descriptions of how the pager and swapper work. The complexity of those two systems, and the reasoning behind how they're designed is more than can easily be answered on an email list. -- Bill Moran Potential Technologies http://www.potentialtech.com