Date: Thu, 25 Jan 2007 19:24:48 -0700 (MST) From: "M. Warner Losh" <imp@bsdimp.com> To: current@freebsd.org Subject: Interesting speed benchmarks Message-ID: <20070125.192448.-432840241.imp@bsdimp.com>
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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: When the enclosure was attached as firewire, I got these numbers: dd if=/dev/da0 of=/dev/null bs=1m count=1000 1048576000 bytes transferred in 25.867655 secs (40536183 bytes/sec) 1048576000 bytes transferred in 25.886887 secs (40506068 bytes/sec) 1048576000 bytes transferred in 25.880712 secs (40515733 bytes/sec) when it was attached via usb (same disk): dd if=/dev/da1 of=/dev/null bs=1m count=1000 1048576000 bytes transferred in 91.098764 secs (11510321 bytes/sec) <gave up waiting for other runs> and for comparison (apples to oranges, I know): dd if=/dev/ad0 of=/dev/null bs=1m count=1000 1048576000 bytes transferred in 32.173160 secs (32591639 bytes/sec) 1048576000 bytes transferred in 32.139310 secs (32625965 bytes/sec) 1048576000 bytes transferred in 32.114549 secs (32651120 bytes/sec) Summary: firewire 40.5 MB/s usb 11.5 MB/s ata 32.6 MB/s So why the huge difference? This is all the more amaizing because 400Mb/s is 50MB/s.[*] Warner P.S. This is on my amd64 laptop, which may be why ata didn't do so well. P.P.S: ad0: 114473MB <FUJITSU MHV2120AT PL 008300A1> at ata0-master UDMA100 firewire: da0: <Maxtor 6 B200R0 BAH4> Fixed Direct Access SCSI-0 device da0: 40.000MB/s transfers da0: 194481MB (398297088 512 byte sectors: 255H 63S/T 24792C) usb: da1: <Initio 6B200R0 2.35> Fixed Direct Access SCSI-0 device da1: 40.000MB/s transfers da1: 194481MB (398297088 512 byte sectors: 255H 63S/T 24792C) P.P.P.S. M == 10^6 here.
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