Re: Network throughput too low?
Mart van de Wege wrote:
> Folks,
>
> A minor question, possibly OT: for some reason I'm getting a very low
> network throughput between my laptop and my desktop machine. I just ran a
> test with netpipe-tcp, and the maximum speed is some 15Mbps. As I have a
> 3Com 905C in the desktop box and a 3Com 574 PCMCIA card on the laptop
> (both are 10/100 NICs) I would have expected a bit more speed here. Also,
> my laptop complains about dropped interrupts during the test, and a quick
> look with ifconfig shows that it is having buffer overruns. Is this
> related? Anyone got a clue as to what is going on and how I can boost my
> network performance?
I haven't looked up the 3com 574, but is it PCMCIA or CardBus? If it's
PCMCIA(the older standard), that 15Mbps sounds quite reasonable. I have a
Xircom 56K + 10/100 combo card in my laptop, that is pcmcia, and i top out at
about 1600-1700kps. PCMCIA is limited to about 2 meg per second, if i recall
correctly. My old SVEC 10/100 card had the same dropped interrupts as what
you report, the Xircom is much faster and doesn't do that.
>From the PCMCIA howto (http://www.linuxdoc.org/HOWTO/PCMCIA-HOWTO-4.html)
16-bit PCMCIA cards have a maximum performance of 1.5-2 MB/sec. That
means that any 16-bit 100baseT card (i.e., any card that uses the pcnet_cs,
3c574_cs,
smc91c92_cs, or xirc2ps_cs driver) will never achieve full 100baseT
throughput. Only CardBus network adapters can fully exploit 100baseT data
rates.
Hope this helps,
Mike Dresser
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