Re: netperf & transmit path performance

From: Kallol Biswas (kallol@bugula.fpk.hp.com)
Date: Wed May 31 2000 - 13:06:42 EST


Thank you for your reply, but I displayed all the counters after
running netperf. There were no collisions, no error, no
discarded frame.

>
> Kallol Biswas <kallol@bugula.fpk.hp.com> writes:
> >
> > Over a half duplex 10Mbps connection:
> > TCP STREAM TEST to 198.168.10.67
> > Recv Send Send Utilization Service Demand
> > Socket Socket Message Elapsed Send Recv Send Recv
> > Size Size Size Time Throughput local remote local remote
> > bytes bytes bytes secs. 10^6bits/s % L % L us/KB us/KB
> >
> > 57344 57344 4096 300.07 6.96 3.52 2.16 41.461 101.728
> >
> > I am a bit concerned about the throughput over half duplex 10Mbps connection.
> > Could some body tell how throughput can go low at 10Mbps?
>
> Collisions of the data with the acks. The TCP ack clock gets out of sync.
>
> >
> > Simon Andrew Boggi got similar result over a half duplex connection
> > with eepro100.
> >
> > With 21143 based card we get the throughput around
> > 9.2 on 10Mbps. I do not know if there is any problem with 82559 in half duplex mode.
>
> The 21143 uses a special patented Ethernet collision backoff algorithm that
> works better than the normal backoff. The 82559 probably doesn't.
>
> Morale: half duplex hurts.
>
> -Andi
>

--
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Telnet: 1-443-7469
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