Date: Thu, 20 Feb 1997 18:11:08 +1030 (CST) From: Michael Smith <msmith@atrad.adelaide.edu.au> To: bde@zeta.org.au (Bruce Evans) Cc: bde@zeta.org.au, msmith@atrad.adelaide.edu.au, hardware@freebsd.org, se@freebsd.org Subject: Re: _big_ IDE disks? Message-ID: <199702200741.SAA17125@genesis.atrad.adelaide.edu.au> In-Reply-To: <199702200437.PAA19813@godzilla.zeta.org.au> from Bruce Evans at "Feb 20, 97 03:37:15 pm"
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Bruce Evans stands accused of saying:
> >
> >Yup, this was a basic criteria for it being used instead of a SCSI
> >disk; by the time you compensate for the extra CPU overhead, I figured
> >that it would make a reasonable alternative to a ~3M/sec SCSI disk
> >(which was not available 8( )
>
> The DORS-32160 is 5-6MB/sec, but you only nead a FireballTM to compete
> with that on transfer speed :-).
I was contemplating the fireballs, but the image wasn't really what I
wanted to pass on to people who expect the machine to be reliable 8)
Given your previous nasty remarks about IDE disks and CPU overhead (the
machine runs several concurrent compute-heavy jobs) and prior experience
with SCSI vs IDE in these systems, I wanted to go as far as possible up
the IDE performance curve.
> >How do I go about ascertaining this? npx0 is enabled, and the kernel
> >was build with I586_CPU defined (obviously). The kernel it's running
> >is built with npx.c v 1.31.2.5.
>
> I can't think of a better way than using `cvs log'. It was reenabled
> in npx.c 1.31.2.6. Other ways: run a debugger and look at the vectors.
> Run `dd if=/dev/zero of=/dev/null bs=1m count=1000' and complain if
> the throughtput is much lower than 120MB/sec.
Hmm, 85MB/sec beforehand, 131MB/sec with a new kernel. Thanks for the
pointer.
New test results :
wdc0: unit 0 (wd0): <Maxtor 85120 A8 ->, 32-bit, multi-block-16
wd0: 4884MB (10003392 sectors), 9924 cyls, 16 heads, 63 S/T, 512 B/S
Writing the 128 Megabyte file, 'iozone.tmp'...15.578125 seconds
Reading the file...14.953125 seconds
IOZONE performance measurements:
8615781 bytes/second for writing the file
8975898 bytes/second for reading the file
-------Sequential Output-------- ---Sequential Input-- --Random--
-Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
Machine MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU /sec %CPU
100 3939 72.4 8105 24.5 2026 10.7 4427 71.1 8175 20.3 93.7 3.5
Throughput's not up, but CPU overhead is down. Perhaps we've hit the
drive's limit?
> Bruce
--
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