Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!seismo!husc6!mit-eddie!genrad!decvax!decwrl!sun!guy
From: guy@sun.UUCP
Newsgroups: net.unix-wizards
Subject: Re: Which commands (in /bin & /usr/bin) must have set user ID (for root)
Message-ID: <8573@sun.uucp>
Date: Mon, 27-Oct-86 13:42:53 EST
Article-I.D.: sun.8573
Posted: Mon Oct 27 13:42:53 1986
Date-Received: Mon, 27-Oct-86 23:18:40 EST
References: <115@tijc02.UUCP> <735@hropus.UUCP> <1040@ho95e.UUCP> <8545@sun.uucp> <1082@cit-vax.Caltech.Edu>
Organization: Sun Microsystems, Inc.
Lines: 15

> /etc/update's liking for holding certain directories open all the time
> causes similar problems when those directories are updated.  I've never
> understood the purpose of that.

Back in the days of V7, UNIX didn't treat the list of free inode table
entries as an LRU cache for inodes.  Holding selected directories open
kept their inodes in core, and meant the system didn't have to go to the
disk every time it wanted to get that inode.  Of course, when you have two
processors (or processes) sharing access to some data structure, and keeping
local cached copies of that data structure, you have to be careful to avoid
cache consistency problems like the ones you see when dual-porting.
-- 
	Guy Harris
	{ihnp4, decvax, seismo, decwrl, ...}!sun!guy
	guy@sun.com (or guy@sun.arpa)