Subject: Re: seemingly dismal performance of NetBSD-1.1A/sun3 file I/O....
To: None <current-users@NetBSD.ORG, Todd.Williamson@cs.cmu.edu>
From: Brad Walker <email@example.com>
Date: 04/10/1996 23:32:36
> From: Todd.Williamson@cs.cmu.edu
> To: current-users@NetBSD.ORG
> Subject: Re: seemingly dismal performance of NetBSD-1.1A/sun3 file I/O....
> CC: current-users@NetBSD.ORG
> Actually, I was doing some disk benchmarking a couple of weeks ago,
> and found the same thing as someone else on the list reported:
> performance through the filesystem seems pretty bad on a 486.
> My machine:
> 486dx4/100, 24 MB, BT-445C VLB SCSI, Quantum 1080S and 240S
> dd gave me around 3 MB/sec.
> IOZONE reported high numbers for small files (around 10 MB/sec for 1
> MB - I assume that everything was cached), and leveled off to a dismal
> 1.2 MB/sec as the file size got larger.
> Any ideas on where this slowdown is coming from?
> Todd Williamson
> Robotics Institute
> Carnegie Mellon University
If your hitting the disk pretty hard then you are getting good number.
What do you expect, 10MB/sec? Remember you can only get as fast as you
hit a cache or the disk drive gives you the bits.
The rate you get over the SCSI bus is much slower than the spindle
bit rate. Unless, you hit the disk drive cache, in which case you
get fast rates.