Messages in this thread | | | From | David Brownell <> | Subject | Re: usbnet ethernet duplex issue? | Date | Fri, 17 Jun 2005 12:39:24 -0700 |
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On Friday 17 June 2005 12:27 pm, Matt Mackall wrote: > > So the question is, what's up with duplex? Everything I can find about > the hardware (including the ASIX datasheet) claims it's full-duplex > capable but aside from the error counters, it's really behaving like a > half-duplex device.
Well, USB itself is half duplex, but that wouldn't explain the issue you're seeing. Maybe David Hollis or Phil Chang, who've both worked with the ASIX parts, can cast some light on their quirks. This is on a 2.6 kernel, I hope ... 2.4 kernels have packet queues a bit too high up in the stack to get any real I/O overlap.
I know that when I've done "ttcp" Linux-to-Linux using a net2280 PCI card [1] using CDC Ethernet protocols, I can get a bidirectional transfer rate of around 25 Mbyte/sec (maybe a bit more, I forget; that's untuned), so the bottleneck isn't the network or USB stacks.
- Dave
[1] http://store.yahoo.com/plxtech/net2280evb.html - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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