Path: utzoo!attcan!uunet!husc6!cmcl2!brl-adm!brl-smoke!gwyn
From: gwyn@brl-smoke.ARPA (Doug Gwyn )
Newsgroups: comp.unix.wizards
Subject: Re: Why UNIX I/O is so slow (was VAX vs SUN 4 performance)
Message-ID: <8124@brl-smoke.ARPA>
Date: 18 Jun 88 02:22:43 GMT
References: <22957@bu-cs.BU.EDU> <14968@brl-adm.ARPA> <601@modular.UUCP> <23288@bu-cs.BU.EDU> <7980@alice.UUCP> <23326@bu-cs.BU.EDU> <6963@cit-vax.Caltech.Edu> <441@mn-at1.k.mn.org>
Reply-To: gwyn@brl.arpa (Doug Gwyn (VLD/VMB) <gwyn>)
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 11

In article <441@mn-at1.k.mn.org> alan@mn-at1.UUCP (0000-Alan Klietz) writes:
-Berkeley should start over.  The whole business with "cylinder groups"
-tries to keep sets of blocks relatively near each other.  With the new
-disks today, the average SEEK TIME IS OFTEN FASTER THAN THE ROTATIONAL
-DELAY.  You don't want to keep blocks "near" each other, instead you want
-to make each extent as large as possible.  Sorry, but cylinder groups are
-archaic.

Such considerations should lead to the conclusion that each type of
filesystem may need its own access algorithms (perhaps in an I/O
processor).  This is easy to arrange via the File System Switch.