From owner-freebsd-performance@FreeBSD.ORG Fri Nov 9 13:37:49 2012 Return-Path: Delivered-To: freebsd-performance@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 8187F4AA for ; Fri, 9 Nov 2012 13:37:49 +0000 (UTC) (envelope-from ap@bnc.net) Received: from mailomat.net (mailomat.net [81.20.89.254]) by mx1.freebsd.org (Postfix) with ESMTP id 0F18E8FC08 for ; Fri, 9 Nov 2012 13:37:48 +0000 (UTC) X-Mailomat-SpamCatcher-Score: 2 [X] X-Mailomat-Junk-Score: 0 [] X-Mailomat-Cloudmark-Score: 0 [] Received: from [194.39.192.125] (account bnc-mail@mailrelay.mailomat.net HELO bnc.net) by mailomat.net (CommuniGate Pro SMTP 5.4.5) with ESMTPSA id 59002872; Fri, 09 Nov 2012 14:37:47 +0100 X-Junk-Score: 2 [X] X-SpamCatcher-Score: 2 [X] Received: from [192.168.200.191] (account ap@bnc.net HELO [192.168.200.191]) by bnc.net (CommuniGate Pro SMTP 6.0c1) with ESMTPSA id 6870459; Fri, 09 Nov 2012 14:40:37 +0100 Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 6.1 \(1498\)) Subject: Re: Compressed RAM disk swap space From: Achim Patzner In-Reply-To: <509CF81F.7090803@yahoo.co.uk> Date: Fri, 9 Nov 2012 14:37:46 +0100 Content-Transfer-Encoding: quoted-printable Message-Id: References: <509CF81F.7090803@yahoo.co.uk> To: David X-Mailer: Apple Mail (2.1498) Cc: freebsd-performance@freebsd.org X-BeenThere: freebsd-performance@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Performance/tuning List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 09 Nov 2012 13:37:49 -0000 Am 09.11.2012 um 13:33 schrieb David : > Hi, I have tried something which actually boosts performance It doesn't; it just moves the load from one limited resource (RAM) to = another one (CPU cycles), adding its own overhead on the way. It just = means that your machine got too large an engine for your tires. Save on = CPU power and get more RAM next time. > : a compressed RAM disk used as swap space. It nearly sounds as good as "hey, we've got virtual memory, let's = generate an incredibly large RAM disk". To me it sounds like investing = into sovereign debt of your home country and paying your interest rate = with your own increased taxes. Why swap into RAM if your process could = use it as well? About the cost of compression: This idea was already annoying decades = ago (doesn't anyone remember those "RAM extenders" for MS-DOS that gave = you "more RAM than your computer contains"?) when software suddenly got = inexplicably slow (until you found the driver chewing on its own tail by = trying to decompress itself) and was one of the reasons I moved to SCO = and BSD/386. Achim