From oracle-l-bounce@freelists.org Fri Oct 22 18:53:19 2004 Return-Path: Received: from air189.startdedicated.com (root@localhost) by orafaq.com (8.11.6/8.11.6) with ESMTP id i9MNrJk25594 for ; Fri, 22 Oct 2004 18:53:19 -0500 X-ClientAddr: 206.53.239.180 Received: from turing.freelists.org (freelists-180.iquest.net [206.53.239.180]) by air189.startdedicated.com (8.11.6/8.11.6) with ESMTP id i9MNrJI25589 for ; Fri, 22 Oct 2004 18:53:19 -0500 Received: from localhost (localhost [127.0.0.1]) by turing.freelists.org (Avenir Technologies Mail Multiplex) with ESMTP id 6C77772D6BD; Fri, 22 Oct 2004 18:59:29 -0500 (EST) Received: from turing.freelists.org ([127.0.0.1]) by localhost (turing [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 16692-19; Fri, 22 Oct 2004 18:59:29 -0500 (EST) Received: from turing (localhost [127.0.0.1]) by turing.freelists.org (Avenir Technologies Mail Multiplex) with ESMTP id BA7A972D1B6; Fri, 22 Oct 2004 18:59:28 -0500 (EST) DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:reply-to:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:references; b=gbCVYGxEwKjaTufOtL+S8MH2ooRbmclGnTwlsjQR5GD0oV/ikhTBRkHTLT9qM0G4YTVLptobtAKvI4/qMyw++iPswoVYP4/bKwM6XqLAUh3ZU8UH5bWdp/aD0O91hS1i6NaMkbKIoUGZ0DcQ45n36B7Kvn/J94EMnL/95jKb4sY= Message-ID: <40a16b3604102214117a0b00e2@mail.gmail.com> Date: Fri, 22 Oct 2004 14:11:03 -0700 From: sol beach To: ryan_gaffuri@comcast.net Subject: Re: question about cpu usage Cc: "Gogala, Mladen" , oracle-l@freelists.org In-Reply-To: <102220042057.11655.41797428000AE9EF00002D872200750330079D9A00000E09A1020E979D@comcast.net> Mime-Version: 1.0 Content-type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8bit References: <102220042057.11655.41797428000AE9EF00002D872200750330079D9A00000E09A1020E979D@comcast.net> X-archive-position: 11478 X-ecartis-version: Ecartis v1.0.0 Sender: oracle-l-bounce@freelists.org Errors-To: oracle-l-bounce@freelists.org X-original-sender: sol.beach@gmail.com Precedence: normal Reply-To: sol.beach@gmail.com X-list: oracle-l X-Virus-Scanned: by amavisd-new at freelists.org It is not as simple as you might initially think it is. Consider that in reality, saying a CPU is 50% busy/idle is somewhat nonsensical. Either is it doing useful work (at the request of the OS) [100% busy] or it is idle [0% busy]. At any & EVERY point in time the CPU is either 100% or 100% idle; nothing in between. Now over a period of time it could be busy half the time (50% busy & 50% idle). What happens if 10 different folks concurrently as the CPU to do work for them? The answer is that 9 folks go into the CPU-wait queue. As system system statistics display the reality the CPU is approaching 100% busy, users may or may not experience a degredation in response time. It all depends on the charateristics of the work load. It might even depend upon the law of large number. HTH & YMMV! On Fri, 22 Oct 2004 20:57:15 +0000, ryan_gaffuri@comcast.net wrote: > ok i will refine the question. > Assuming I am at a constant rate X of CPU usage, will there be a declining returns as CPU usage increases to X + n for a constant period of time. > > Assume CPU usage holds steady. CPU u sage is CPU usage. It shouldnt matter what its doing in terms of performance. > > > -------------- Original message -------------- > > > Question asked in such generality really doesn't make much sense and can > > only have one > > answer: it depends. Mostly, it depends on what is CPU doing. Well optimized > > queries will > > typically have a short burst or two of intense CPU activity and then will > > finish. Using > > 100% of CPU power is, unfortunately, also characteristic for "well cached" > > queries which > > can perform a gazillion logical block gets with no phyisical disk reads. An > > example of > > such query is the following: > > -- > http://www.freelists.org/webpage/oracle-l > -- http://www.freelists.org/webpage/oracle-l