distributed performance test

Serge Aleynikov <>
Mon Apr 25 19:26:50 CEST 2005


Thanks Sean,  I'll play with erlsnoop when I have more time.

For now the only outstanding issue I have is listed here:

http://www.erlang.org/ml-archive/erlang-questions/200504/msg00274.html
http://www.erlang.org/ml-archive/erlang-questions/200504/msg00286.html

If you happened to have similar experiences, please do let me know.  :-(

Regards,

Serge

Sean Hinde wrote:
> 
> On 25 Apr 2005, at 17:49, Serge Aleynikov wrote:
> 
>> Sean Hinde wrote:
>>
>>>> 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...
>>>
>>> Well, I guess that a single client is actually only exercising half 
>>> of a duplex. There is never any time when traffic wants to flow both 
>>> ways at the same time.
>>
>>
>> You know, I forgot to mention another interesting fact.  When I tried 
>> to troubleshoot this issue, I extended my test_client/test_server to 
>> be able to send/receive messages using three transports: 
>> erlang/tcp/udp. Here are the results of my tests when the eth0 was set 
>> to half-duplex:
>>
>> ()15> test_client:test_erl(, 10, 500).
>>   -> AvgTime=0.022 (45.360 c/s)
>>
>> ()17> test_client:test_udp({10,227,1,200}, 10, 500).
>>   -> AvgTime=0.000 (3355.705 c/s)
>>
>> ()18> test_client:test_tcp({10,227,1,200}, 10, 500).
>>   -> AvgTime=0.000 (3144.654 c/s)
>>
>> So, if your statement were true, then it would've had impact on all 
>> tcp/udp/erlang transports, wouldn't it?  Yet in this case somehow it 
>> only impacted Erlang's message passing speed.
>>
>> After converting eth0 to full-duplex:
>> ()19> test_client:test_erl(, 10, 500).
>>   -> AvgTime=0.000 (2450.980 c/s)
>>
>> (Note: it's still a bit slower than when using TCP/UDP sockets).
> 
> 
> Yes, this also matches with my experience. In fact it prompted us to 
> write our own simpler RPC mechanism as we needed extreme performance for 
> one of our applications.
> 
> It would be interesting to run profilers and trace to see where the 
> extra time has gone. I have never used it, but erlsnoop might be helpful:
> 
> http://www.erlang.org/contrib/erlsnoop-1.0.tgz
> 
> Sean



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