From owner-freebsd-current Tue Feb 4 14:58:12 2003 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 BA03037B401; Tue, 4 Feb 2003 14:58:10 -0800 (PST) Received: from dan.emsphone.com (dan.emsphone.com [199.67.51.101]) by mx1.FreeBSD.org (Postfix) with ESMTP id 2193043E4A; Tue, 4 Feb 2003 14:58:10 -0800 (PST) (envelope-from dan@dan.emsphone.com) Received: (from dan@localhost) by dan.emsphone.com (8.12.6/8.12.6) id h14Mw4a1028730; Tue, 4 Feb 2003 16:58:04 -0600 (CST) (envelope-from dan) Date: Tue, 4 Feb 2003 16:58:04 -0600 From: Dan Nelson To: Poul-Henning Kamp Cc: current@FreeBSD.ORG Subject: Re: Preview: GEOMs statistics code. Message-ID: <20030204225804.GC32075@dan.emsphone.com> References: <25779.1044395087@critter.freebsd.dk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <25779.1044395087@critter.freebsd.dk> X-OS: FreeBSD 5.0-CURRENT X-message-flag: Outlook Error User-Agent: Mutt/1.5.3i 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 In the last episode (Feb 04), Poul-Henning Kamp said: > Collecting number of operations and number of errors is a nobrainer. > > The timestamps cost something to make, and my plan was to only > collect them while a monitoring program is running. (Is this a good > idea ?) > > In difference from the devstat framework which measures how big a > percentage of the time a drive has one or more outstanding requests, > I think that measuring the responstime is a much more useful metric. > (comments, input, references welcome) Can we do both? :) %busy is a nice value if only because it's a nice value to put on a status meter. If you're already timing each transaction it won't cost much. According to the devstat source, timestamping is cheap relative to actually doing math on the values (end_transaction always gets the time, but only uses the value when busy_count goes from >0 to 0). Is this right? > I pressume we also want to collect number of bytes transferred, and > I will add that in the next iteration. Definitely. What I'd like is enough statistics to be able to duplicate Solaris' iostat -x output: extended device statistics device r/s w/s kr/s kw/s wait actv svc_t %w %b r/s, kr/s reads/sec and Kbytes/sec wait = average number of transactions waiting for service actv = average number of transactions actively being serviced svc_t = average time per I/O %w = percent time there are transactions waiting for service %b = percent of time the disk is busy wait and %w may zero on FreeBSD. Do we allow queuing more transactions than the physical device supports? -- Dan Nelson dnelson@allantgroup.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message