From owner-freebsd-stable@FreeBSD.ORG Thu Nov 29 19:20:28 2007 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 69B4D16A421 for ; Thu, 29 Nov 2007 19:20:28 +0000 (UTC) (envelope-from kris@FreeBSD.org) Received: from weak.local (freefall.freebsd.org [IPv6:2001:4f8:fff6::28]) by mx1.freebsd.org (Postfix) with ESMTP id 865BC13C459; Thu, 29 Nov 2007 19:20:27 +0000 (UTC) (envelope-from kris@FreeBSD.org) Message-ID: <474F1105.5020708@FreeBSD.org> Date: Thu, 29 Nov 2007 20:20:37 +0100 From: Kris Kennaway User-Agent: Thunderbird 2.0.0.9 (Macintosh/20071031) MIME-Version: 1.0 To: Matt Reimer References: <474F0BDF.8070605@FreeBSD.org> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: freebsd-stable@freebsd.org, Pete French Subject: Re: Also seeing 2 x quad-core system slower that 2 x dual core X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 29 Nov 2007 19:20:28 -0000 Matt Reimer wrote: > On Nov 29, 2007 10:58 AM, Kris Kennaway wrote: >> Pete French wrote: >>> On the dual core processors this takes about 20 seconds. On the quad >>> cores it takes about 3 minutes! This is true for both the 32 and 64 bit >>> versions of FreeBSD :-( >> That almost certainly has nothing to do with how many CPUs your system >> has, since rm -rf is a single process running on a single core. > > I wonder if I'm seeing this too. Running super-smack on a 2 x quad > core 1.6GHz Dell 1950 I get about 40000 qps, whereas on a 2 x dual > core 3.0GHz box I've seen 80000 qps. Please, let's try to stay focused :) rm -rf has nothing to do with super-smack and vice versa. > Is this expected? It is not very surprising. super-smack is not a good SMP benchmark, it does stupid things like 1-byte I/O, so it is not very scalable nor a good model of real-world database activity. Accounting for your CPUs being twice as fast on the dual core, it roughly says that the benchmark is not scaling beyond 4 CPUs, which is in line with my own observations. Kris