Re: Slow receive with AX8817 USB2 ethernet adapter

[mru@kth.se (Måns Rullgård)]

David T Hollis <dhollis@davehollis.com> writes:

> On Wed, 2004-01-07 at 10:54, David T Hollis wrote:
>> On Wed, 2004-01-07 at 08:53, Måns Rullgård wrote:
>> > mru@kth.se (Måns Rullgård) writes:
>> > 
>> > > I'm getting very bad receive rates with a Netgear FA-120 USB2 Ethernet
>> > > adapter under Linux 2.6.0.  Timing an incoming TCP stream, I get only
>> > > 600 kB/s.  Sending works properly at 10 MB/s.  I first reported this
>> > > problem some time in July or August.  Is it just me having this issue?
>> > > Can I get any helpful information somehow?
>> > 
>> Hmm, I am seeing the same results using ttcp:
>> 
> Some more results.  This time I walked away for a few minutes, came back
> and ran the test again and started getting the 10MB numbers again.  No
> driver unload, etc.  Interesting thing is the I/O calls and time per
> call.  I'm curious as to whether  the varying results are tied to memory
> allocation, locking, or what.

Just a very unscientific observation: my laptop emits a noise when the
ethernet is used.  The pitch depends on the transfer rate.  When
communicating with a working machine, and receiving from the ax8817,
there is a continuous high-pitch sound.  When sending to the ax8817,
the sound has a much lower pitch (not surprising) and is also
intermittent with bursts lasting < 1/2 second followed by an
approximately 1/2 second pause.  The lights on the switch behave
similarly.

-- 
Måns Rullgård
mru@kth.se