Path: utzoo!utgpu!watmath!onfcanim!dave
From: dave@onfcanim.UUCP (Dave Martindale)
Newsgroups: comp.unix.aux
Subject: Re: Some questions about A/UX
Message-ID: <16775@onfcanim.UUCP>
Date: 24 Nov 88 00:03:43 GMT
References: <941@ccnysci.UUCP> <19528@apple.Apple.COM> <964@ccnysci.UUCP> <19816@apple.Apple.COM> <1011@ccnysci.UUCP> <21057@apple.Apple.COM>
Reply-To: dave@onfcanim.UUCP (Dave Martindale)
Organization: National Film Board / Office national du film, Montreal
Lines: 29

In article <21057@apple.Apple.COM> phil@Apple.COM (Phil Ronzone) writes:
>
>OPEN QUESTION - why do you think the "Mac is not going as fast as it should"?
>If this is on a comparsion basis, tell me the equivalent machine that runs
>faster. Equivalent means 68020, ~16MHz, memory management, SCSI disk I/O,
>SVR2, etc. We really do want to know of equivalent hardware that runs better
>because of software. When we find it, we want to make ours run faster too.

The Silicon Graphics IRIS 3000 series uses a 16 MHz 68020, with memory
management.  The old 70 Mb disks use an ST506 interface - SCSI should
do better.  The kernel is basically system V release something, and they
get several times the disk throughput of A/UX.

Why?  Basically because they don't use the system V filesystem - they
replaced it with an extent-based filesystem that reads and writes
much larger data blocks at a time.  I believe that the only way A/UX
will get decent performance out of the disk is by switching to a
different filesystem.

Note that using the Bell filesystem cripples NFS performance too,
since all reads and writes are done 1 Kb at a time, instead of the
4 or 8 Kb that other workstations use.  So it matters even when you
aren't using the local disk.

If you change filesystems and quadruple disk throughput, DMA may become
important for disk I/O.  Or it might not.  But for the moment, the filesystem
software seems to be the problem.

	Dave Martindale