distributed performance test
Mon Apr 25 17:55:01 CEST 2005
Thank you, thank you, thank you!!!
The devlinuxpro2 Linux server was indeed running eth0 in 100BaseTX
After I set the interface to full-duplex, and rebooted, the speed tests
ran as expected.
P.S. The only question I have remaining is why would half-duplex setting
not have any speed impact on a single client talking to a synchronous
server, but only on multiple clients...
Sean Hinde wrote:
> On 25 Apr 2005, at 10:30, Matthias Lang wrote:
>> Sean Hinde writes:
>>> We have seen such problems when networks/NICs are set up incorrectly
>>> (e.g. one end forced to 10/half duplex, the other to 100/full
>> Methinks the details have gotten messed up in your memory.
> That, or perhaps it was an expression of artistic licence designed to
> increase the impact. Clearly such flights of fancy get the drubbing they
> deserve on this mailing list :-)
> (BTW I have copied the list on your answer because this is actually
> quite useful information)
>> There's no way you can have one end at 10Mbit and the other at 100 and
>> still have communication (10Mbit uses manchester coding, 100Mbit uses
>> something completely different).
>> You're probably remembering one end forced to 100/full duplex with no
>> autonegotiation and other end on autonegotiate. One end then uses
>> 100/full and the other 100/half---the standard requires this (broken)
> Very interesting. This figures more closely with my real memory. We have
> seen this (I was told, by another well meaning techie) when
> auto-negotiation didn't "work properly" with Solaris, meaning that both
> ends need to be pinned to the same settings. I never dug very deeply,
> and the UNIX guys always needed to fix it, but it sounds like the UNIX
> guys were fixing a problem caused by the network guys.
> On reflection that sounds about right.
>> The clearest symptom is that the half-duplex side sees late
>> collisions. _Late_ collisions should never be present on an ethernet.
>> Up higher, you see TCP connections which have occasional low
>> throughput and difficulty getting started.
>> I've seen this twice in the field, both times it's involved an
>> expensive switch and a well-meaning techie who insisted on configuring
>> everything for "maximum performance".
| Serge Aleynikov Tel: (973) 438-3436
| MIS Telecom Fax: (973) 438-1457
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