From owner-freebsd-smp Wed Feb 27 12:36:12 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 DB06937B402; Wed, 27 Feb 2002 12:36:06 -0800 (PST) Received: from NewStorm.whitebarn.com (NewStorm.whitebarn.com [216.0.13.77]) by smtp.whitebarn.com (8.9.3/8.9.3) with ESMTP id OAA55865; Wed, 27 Feb 2002 14:35:29 -0600 (CST) (envelope-from Bob@Talarian.Com) Subject: Re: Performance vs. Stable From: Bob Van Valzah To: Kelly Yancey Cc: Bruce Evans , Robert Watson , Jorge Aldana , Garance A Drosihn , smp@FreeBSD.ORG In-Reply-To: <20020227121320.X8086-100000@gateway.posi.net> References: <20020227121320.X8086-100000@gateway.posi.net> Content-Type: text/plain Content-Transfer-Encoding: 7bit X-Mailer: Evolution/1.0.2 Date: 27 Feb 2002 14:35:29 -0600 Message-Id: <1014842130.2359.113.camel@NewStorm.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 Maybe Bruce's version of lmbench reports data differently that my (old) version does? I was surprised by this too so I checked to make sure that the numbers were absolute. My first round of test showed -CURRENT taking 10 ms while -STABLE took 61 ms for a "null" system call. Alas when I went to verify my results by rerunning them on -STABLE, I got different results. In fact, I got 10 ms. I guess I submit a paper to the Journal of Irreproducible Results (www.jir.com) :-) So here's the latest run: (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 4.7 3.6 3.7 5.6 8.4 9.9 TwinHead FreeBSD 4.5-S 233 *10 *1.1K *5.6K *9.6K *38 *12 *15 TwinHead. FreeBSD 5.0-2 233 *10 1.5 1.3 1.3 1.3 3.9 7.2 The top line is -CURRENT with WITNESS and friends. The bottom line is -CURRENT without WITNESS. The middle line is -STABLE. So the way I'm reading it now is that (once you get WITNESS out of the way) there's little difference in system call overhead between -STABLE and -CURRENT. Lmbench "process" numbers seem 30-50% slower on -CURRENT. The context switch numbers are still 4x to 7x slower on -CURRENT. I've hooked back up with Larry and will be working with him (and I hope Bruce Evans) to get a solid version of lmbench and procedures that lead to more reproducible resutls. Bob On Wed, 2002-02-27 at 14:16, Kelly Yancey wrote: > On Wed, 27 Feb 2002, Bruce Evans wrote: > > > > > > > Processor, Processes - factor slower than the best > > > -------------------------------------------------- > > > > I think you are misinterpreting them. The non-starrd results are > > absolute times. E.g., they say that the "null" syscall takes 6.1 usec > > in 4.5-S and 6.1 usec in -current. This is about right. The "null" > > syscall is actually a write of 1 byte to /dev/null. File i/o has been > > been extensively pessimized in -current using locking. This only > > matters much for small i/o's, which is exactly what the benchmark > > tests. The pessimization is normally reduced a little for device files > > by using devfs. > > > > I know I am going out on a limb to doubt you, but are you sure? The chart > header (as quoted above) sure seems to imply that the starred times are > absolute and all of the others are relative comparisons. As such, I was quite > impressed by how well -current appears to be performing compared to -stable > given how little optimization has been done so far. > > Kelly > kbyanc@{posi.net,FreeBSD.org} To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-smp" in the body of the message