Date: Fri, 26 Jan 2007 14:07:56 -0700 (MST) From: "M. Warner Losh" <imp@bsdimp.com> To: anderson@freebsd.org Cc: freebsd-current@freebsd.org, shoesoft@gmx.net Subject: Re: Interesting speed benchmarks Message-ID: <20070126.140756.-311940260.imp@bsdimp.com> In-Reply-To: <45BA51EA.3070901@freebsd.org> References: <200701261052.12435.shoesoft@gmx.net> <20070126.114944.104080809.imp@bsdimp.com> <45BA51EA.3070901@freebsd.org>
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In message: <45BA51EA.3070901@freebsd.org>
Eric Anderson <anderson@freebsd.org> writes:
: On 01/26/07 12:49, Warner Losh wrote:
: > From: Stefan Ehmann <shoesoft@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
:
:
: A few tidbits of information (may be useful, maybe not):
:
: - I've seen the firewire part of the enclosure be faster than the USB
: part. The chips that run it are possibly different, so that shouldn't
: be forgotten. I've had a few USB->flash adapters that got lousy
: performance, but when I switched to a USB->SATA flash card reader, the
: performance doubled.
I'm now seeing on my FreeBSD desktop at work numbers that are in the
28MB/s range. I'll have to investigate things more closely... I
can't imagine why FreeBSD/amd64 would be so much slower.
: - For those testing using a file system - STOP! It's not a good test of
: the throughput of the device, and depends on a lot of variables. dd or
: diskinfo are decent generic tools, but in Windows you just can't use a
: file system benchmark to compare.
yes.
: - If you read/write less than the drive cache, it should remove the
: latency of the drive from the equation, right?
True, but not relevant, I don't think. the speed of the disk is in
excess of what either firewire or usb can do.
Warner
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