From owner-freebsd-smp Tue Feb 26 19:43:57 2002 Delivered-To: freebsd-smp@freebsd.org Received: from smtp.whitebarn.com (Spin.whitebarn.com [216.0.13.113]) by hub.freebsd.org (Postfix) with ESMTP id C33C737B402; Tue, 26 Feb 2002 19:43:47 -0800 (PST) Received: from Relent.Bob.whitebarn.com (Relent.Bob.whitebarn.com [216.0.13.50]) by smtp.whitebarn.com (8.9.3/8.9.3) with ESMTP id VAA47507; Tue, 26 Feb 2002 21:43:45 -0600 (CST) (envelope-from Bob@Talarian.Com) Subject: Re: Performance vs. Stable From: Bob Van Valzah To: Robert Watson Cc: Jorge Aldana , Garance A Drosihn , smp@FreeBSD.ORG In-Reply-To: References: Content-Type: text/plain Content-Transfer-Encoding: 7bit X-Mailer: Evolution/1.0.2 Date: 26 Feb 2002 21:43:45 -0600 Message-Id: <1014781427.15635.10.camel@Relent.Bob.WhiteBarn.Com> Mime-Version: 1.0 Sender: owner-freebsd-smp@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org On Tue, 2002-02-26 at 19:50, Robert Watson wrote: > It's worth noting that WITNESS can have a dramatic impact on performance. > I actually turned it off by default recently, and it got turned back on > again (for good reasons). Any benchmarking must be done without those > settings turned on. Allow me to quantify the difference and show a more valid comparison to -STABLE as well. (Best numbers are starred, i.e., *123) Processor, Processes - factor slower than the best -------------------------------------------------- Host OS Mhz Null Null Simple /bin/sh Mmap 2-proc 8-proc Syscall Process Process Process lat ctxsw ctxsw --------- ------------- ---- ------- ------- ------- ------- ---- ------ ------ TH.Witnes FreeBSD 5.0-2 232 11 3.1 2.8 2.8 4.2 3.7 4.9 TwinHead FreeBSD 4.5-S 228 6.1 2.2 1.9 1.9 2.4 *27 *30 TwinHead. FreeBSD 5.0-2 233 *10 *1.7K *7.3K *12.6K *51 1.7 3.6 The top line is -CURRENT with WITNESS and friends turn on. The bottom line is -CURRENT with them turned off. The middle line is -STABLE. I'm surprised by the results here. (Maybe I'm misinterpreting them?) It looks like -CURRENT is over 6x faster than -STABLE on null system calls. Forks and mmap seem about 2x faster but context switches are slower. It's interesting to note that WITNESS and friends slowed down null system calls by 11x and other kernel operations by about 3-5x. Bob To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-smp" in the body of the message