From owner-freebsd-current Tue Oct 29 13: 6:38 2002 Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id A669937B401 for ; Tue, 29 Oct 2002 13:06:37 -0800 (PST) Received: from apollo.backplane.com (apollo.backplane.com [216.240.41.2]) by mx1.FreeBSD.org (Postfix) with ESMTP id 4FAA143E3B for ; Tue, 29 Oct 2002 13:06:37 -0800 (PST) (envelope-from dillon@apollo.backplane.com) Received: from apollo.backplane.com (localhost [127.0.0.1]) by apollo.backplane.com (8.12.5/8.12.5) with ESMTP id g9TL6aFC010662; Tue, 29 Oct 2002 13:06:36 -0800 (PST) (envelope-from dillon@apollo.backplane.com) Received: (from dillon@localhost) by apollo.backplane.com (8.12.5/8.12.5/Submit) id g9TL6aoc010659; Tue, 29 Oct 2002 13:06:36 -0800 (PST) (envelope-from dillon) Date: Tue, 29 Oct 2002 13:06:36 -0800 (PST) From: Matthew Dillon Message-Id: <200210292106.g9TL6aoc010659@apollo.backplane.com> To: Terry Lambert Cc: Raymond Kohler , current@FreeBSD.ORG Subject: Re: questions about the state of current References: <2570443.1035916854787.JavaMail.wshttp@emss03g01.ems.lmco.com> <3DBEF55E.A0F9ED1B@mindspring.com> Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG :Most of the speed difference is WITNESS, INVARIANTS, and other :debugging code that's turned on by default in the config files :for -current. You can turn most of it off. That said, -current :is slower than -stable in a number of places, so expect some :slowdown, if you are running non-concurrent code. I would concur with this diagnosis. With witness turned off -current is around 15% slower then -stable for general purpose computing, like a 'make buildworld -j 20', and I expect that -stable will beat out -current on single-cpu boxes for a long time to come. That said, it should be noted that nearly all the really cool development projects are only happening in -current. Things like KSEs, hardware crypto support, UFS2, and so forth, only exist in -current. Very little of this work is going to be MFC'd so depending on your needs -current could very well end up faster. And, of course, there is the fact that computing power seems to double every year. Since -current's overhead is in large part due to mutexes and other concurrency mechanisms, and these are literally pure-cpu mechanisms rather then memory or I/O dependant, decisions should be based on capability rather then something as insignificant as a 15% performance difference between the 'rough cut' -current and the well aged -stable. In coming years concurrency is going to become the leading performance-improving mechanism for computers. -Matt To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message