bkbits.net is down
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From: Alan Cox Date: 2003-06-28 23:13:55Quoted 2 lines · Dr. David Alan Gilbert
Hmm - why should it suck so badly? Shouldn't USB 2 (yes I mean the 480Mbps) manage 40MByte/s+ ?
Custom devices certainly have done that, with drivers that keep everything busy. Last fall, one person reported 38+ MB/sec from a VT8235. The theoretical peak bandwidth for bulk traffic (what most folk want) is 52 MByte/sec.
A Western Digital drive I tried gave me 27 MByte/sec with USB. And I hate to say that the FireWire mode didn't work at all, since I was curious how they'd compare! (2.5.71 or so.)
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I don't think you get the full 480Mbit/sec on a single device. 5Mbyte/sec is a bit low
Some combinations of EHCI silicon, USB-to-IDE adapter, and IDE work better than others ... I once switched a drive from one EHCI controller to another (same host and OS, didn't reboot), and went from 5 MB/s to 19 MB/sec. That was on 2.4; with the 2.5 usb-storage, both controllers gave the higher speed.
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but that may be some of the remaining work on
the USB EHCI drivers. I've not tried 2.5.x which may be way better here.
The key difference in 2.5 is that usb-storage queues requests, no more slow page-at-a-time I/O. It's the same EHCI driver underneath, lately -- much improved since last September (or so) when it first started to generate real user feedback.
- Dave