Subject: Re: Disk performance under NetBSD on A3000
To: Stephen J. Roznowski <firstname.lastname@example.org>
From: Eduardo E. Horvath email@example.com <firstname.lastname@example.org>
Date: 04/24/1995 08:36:43
On Sun, 23 Apr 1995, Stephen J. Roznowski wrote:
> I'm seeing poor disk performance under NetBSD-current on my A3000.
> Under ADOS, I see about 1.7-2.0 megabytes per second (via sysinfo)
> while under NetBSD, I see about 500 kilobytes per second
> (dd if=/dev/zero of=zzzzz bs=1024k count=10).
1) You are measuring write performance, not read performance. Writes are
usually 1/2 to 1/4 the speed of reads.
2) You are writing to a file within the filesystem, which involves such
things as file-system overhead, copying from your process space into the
buffer cache, and updating the filesystem structures.
3) You are writing 1K at a time, where the filesystem is using 8K
blocks. This means you will probably be doing 4 writes/block.
> What disk performance numbers are others seeing?
With (dd if=/dev/rs?c of=/dev/null bs=65565) I get on the order of
1.5-2.5MB/s, depending on which drive I access.