Interesting speed benchmarks

[Warner Losh]

From: Stefan Ehmann <shoesoft at gmx.net>
Subject: Re: Interesting speed benchmarks
Date: Fri, 26 Jan 2007 10:52:11 +0100

> On Friday 26 January 2007 03:24, M. Warner Losh wrote:
> > On a lark, I just got a combo USB/Firewire external disk drive.  I ran
> > some crude benchmarks, and I was surprised by what I found.  This is
> > on a fairly stock -current kernel.
> >
> > Firewire does around 40MB/s, while USB 2.0 maxes out at about 12MB/s.
> > This is with a simple dd command:
> 
> On my i386 notebook with USB 2.0 enclosure.
> Linux: 31.5MB/s
> FreeBSD: 27.5MB/s
> 
> There's still room for improvement but numbers don't seem that bad.
> 
> Maybe you should try knoppix or so to verify it's not the drive's fault. Other 
> than that I'd also guess it's an amd64 problem.

It is not an AMD64 problem.  I get the same numbers on my i386 latpop
as I get on my amd64 laptop.  Actually, I get WORSE numbers on the
i386 laptop by about 20%.

It isn't the drive's fault.  Otherwise, firewire wouldn't get 40MB/s.
The same drive, the same enclusure are used for both the USB and
firewire tests.  It is about as apples to apples as you can get.

There's some serious performance issues in the usb stack.

Warner