From owner-freebsd-current@FreeBSD.ORG Sat Apr 29 16:44:57 2006 Return-Path: X-Original-To: freebsd-current@freebsd.org 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 5027116A410; Sat, 29 Apr 2006 16:44:57 +0000 (UTC) (envelope-from rwatson@FreeBSD.org) Received: from cyrus.watson.org (cyrus.watson.org [209.31.154.42]) by mx1.FreeBSD.org (Postfix) with ESMTP id AD6ED43D46; Sat, 29 Apr 2006 16:44:56 +0000 (GMT) (envelope-from rwatson@FreeBSD.org) Received: from fledge.watson.org (fledge.watson.org [209.31.154.41]) by cyrus.watson.org (Postfix) with ESMTP id 62B4646B04; Sat, 29 Apr 2006 12:44:55 -0400 (EDT) Date: Sat, 29 Apr 2006 17:44:55 +0100 (BST) From: Robert Watson X-X-Sender: robert@fledge.watson.org To: Ceri Davies In-Reply-To: <20060429100236.GJ51777@submonkey.net> Message-ID: <20060429174129.H11416@fledge.watson.org> References: <002401c66b0a$44c230e0$01655050@jersey> <44529510.6030704@freebsd.org> <20060428222627.GI51777@submonkey.net> <001801c66b42$d48d4740$e8775050@jersey> <20060429100236.GJ51777@submonkey.net> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Cc: freebsd-arch@freebsd.org, freebsd-current@freebsd.org, Colin Percival , Michael Bushkov Subject: Re: [HEADS UP] upcoming /etc/services updating X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 29 Apr 2006 16:44:57 -0000 On Sat, 29 Apr 2006, Ceri Davies wrote: >> I think, that "perform-actual-lookups" mode should also be enabled for >> "services" by default in cached.conf - so that the cache for services >> information would be the same for all users. > > So "perform-actual-lookups" essentially creates a system-wide cache? > >> Besides, as services information changes extremely rarely, I'd also >> suggest putting greater TTL values for "services" in the cached.conf. > > Yes, the services cache could always be flushed by the superuser after > changing the services data source. Very few sites use distributed services databases (at least, that I've ever seen). Performing stat() on /etc/services to check the last modification date is pretty light-weight, and probably worth doing. What you don't want is someone modifying /etc/services, restarting the daemon immediately, and having it fail due to an added service not being found. Likewise for other local databases. BTW, since this is in the context of significantly increasing the size of the services database, have we: (1) Measured what impact adding the cache daemon for local databases has? Specifically, does adding the cache daemon for a database like /etc/services, /etc/passwd, etc, improve performance, or add overhead? (2) Looked at adding /etc/services.db, similar to the other compiled database pieces, in order to improve lookup times for very large tables. This change would be orthoganal to a cache daemon. Robert N M Watson