Path: utzoo!utgpu!watmath!iuvax!cica!gatech!udel!mmdf
From: HELMER%SDNET.BITNET@vm1.nodak.edu (Guy Helmer)
Newsgroups: comp.os.minix
Subject: Disk performance under Minix
Message-ID: <21290@louie.udel.EDU>
Date: 8 Aug 89 14:48:12 GMT
Lines: 16

Bruce Evans' work on improving floppy disk performance got my curiosity
up, so I did a little unscientific test of i/o to my hard disk under
Minix and PC-DOS.  I wrote a little program that wrote 256 1024-byte
blocks to a file using fopen/fwrite.  Under PC-DOS, this program
took 5 seconds to write the file.  Under Minix, this program took
18 seconds to run.  This is on a 20Mhz 80386 machine with standard
AT-style controller and a 40Mb ST-251 disk with 1:2 interleave.
The 1:2 interleave is optimum for DOS; I suspect that it is too
tight for Minix.  Has anyone tried fiddling with the interleave (or
the AT disk driver) to improve disk i/o?  Does Bruce's protected mode
fixes (with associated improved interrupt code) improve the disk i/o
situation by reducing the time the kernel spends working (thereby improving
the optimum interleave factor)?

-- Guy
   BITNET: HELMER@SDNET