[PATCH][RFC] usbatm.[ch]: cleanup and OAM F5 loopback
castet.matthieu at free.fr
Sat Mar 12 17:10:03 EST 2005
Roman Kagan wrote:
> Nonetheless please let me reiterate the question I asked a while ago: do
> you have an indication that isochronous transfers are better for this
> sort of workload? I'd be surprised if they are. They are meant for
> constant rate data streams with no requirement for data integrity, like
> audio or video. ATM data, on the opposite, is typically variable rate,
> and loosing data on the way from the modem to the host doesn't look
Well, may be it is the sagem that don't work well with bulk mode, but
when it is in high speed mode, if you reach a limit (200-300kb/s), the
modem produce lot's of error, and the atm data trame are broken (crc
error, bogus pdu_length, ...). So because of these errors, the modem
never reach the maximun rate.
In iso rate it work at 700kb/s with no problem.
> Please note that I'm just handwaving here; AFAIK SpeedTouch 330 has iso
> endpoints too, but I'd be really interested to see if it helps a single
> bit... Maybe eagle-usb project has done some measurements?
Like I said 300-400kb/s vs 700kb/s on my computer.
I don't know if there are other measurements.
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