From owner-freebsd-current Tue Feb 4 17:22:19 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 3C76537B401; Tue, 4 Feb 2003 17:22:18 -0800 (PST) Received: from wantadilla.lemis.com (wantadilla.lemis.com [192.109.197.80]) by mx1.FreeBSD.org (Postfix) with ESMTP id 6D3B443F93; Tue, 4 Feb 2003 17:22:16 -0800 (PST) (envelope-from grog@lemis.com) Received: by wantadilla.lemis.com (Postfix, from userid 1004) id 12F245197D; Wed, 5 Feb 2003 11:52:14 +1030 (CST) Date: Wed, 5 Feb 2003 11:52:14 +1030 From: Greg 'groggy' Lehey To: phk@freebsd.org Cc: Brad Knowles , current@freebsd.org Subject: Re: Preview: GEOMs statistics code. Message-ID: <20030205012214.GG12525@wantadilla.lemis.com> References: <27759.1044403667@critter.freebsd.dk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <27759.1044403667@critter.freebsd.dk> User-Agent: Mutt/1.4i Organization: The FreeBSD Project Phone: +61-8-8388-8286 Fax: +61-8-8388-8725 Mobile: +61-418-838-708 WWW-Home-Page: http://www.FreeBSD.org/ X-PGP-Fingerprint: 9A1B 8202 BCCE B846 F92F 09AC 22E6 F290 507A 4223 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 On Wednesday, 5 February 2003 at 1:07:47 +0100, Poul-Henning Kamp wrote: > In message , Brad Knowles writes: >> At 10:44 PM +0100 2003/02/04, Poul-Henning Kamp wrote: >> >>> 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) >> >> This is queue depth versus latency, right? I don't suppose a >> request to provide both would hold any weight with you, would it? > > I'm 100% wide open to suggestions. Anything I can trivally account > for is fair game. It looks like there are at least three statistics of interest: 1. Response time. 2. %busy. I personally think this is the most important one, but as you say, there's no reason not to do the others as well. 3. Average number of requests waiting. > I don't have a queue-depth as such, but I have number of > transactions in transit. Will a snapshot of that at the time of the > read do what you want ? What's the difference? I would have thought that's the same thing. > I won't be locking the stats counters, so reads may get inconsistent > results. This looks like a correct decision to me. I can't see any disadvantage in slightly incorrect values, as long as they don't accumulate. Greg -- See complete headers for address and phone numbers To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message