[mpich-discuss] Scalability of Intel quad core (Harpertown) cluster

[trnja001 at umn.edu]

Your network looks very good for a gigabit network, assuming you tested it 
between different nodes. I'd take a look at the network bandwidth 
utilization (packet loss, etc) during a run and if that doesn't tell you 
anything, then the other suggestions mentioned earlier in the e-mails (such 
as code profiling) would give you the answer.

On Mar 29 2008, Hee Il Kim wrote:

>Hi,
>
>mpi_pong test reuslts show that out gigabit network has
>
>Max rate = 115.335908 MB/sec  Min latency = 49.948692 usec
>
>I ran it several times and got almost the same results. Unfortunately I
>could not analyse more and the reuslt was attached to this mail.
>
>Hee Il
>
>2008/3/29, Elvedin Trnjanin <trnja001 at umn.edu>:
>>
>> You would do that within the code. If you're trying to pass every
>> element of an int array one at a time (message size is sizeof(int)), it
>> will have much worse performance than sending the entire array (message
>> size is sizeof(int)*arraydimensions.
>>
>> Example -
>> http://www.scl.ameslab.gov/Projects/mpi_introduction/figs/mpi_pong.c
>> This is a start for a decent approximation of network bandwidth and
>> latency for a certain message size. Although not accurate, it'll
>> certainly give you an idea of your network's performance with various
>> message sizes and transfer types. It only works on two nodes at a time
>> however so other types of communication like AlltoAll are not tested.
>>
>>
>> Hee Il Kim wrote:
>> >
>> > I checked the bandwidth behavior mentioned by Elvedin. Could I change
>> > or setup the message size and frequency in a runtime level or any
>> > other steps?
>> >
>>
>>
>