Ceilidh ... Re^6: More advanced problem

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Re^6: More advanced problem – p2p fails

Hi,
Alexei, thanks for your hints. I've run a bigger task on the cluster (about 1 hour on 8 cores, UHF optimize task) but results are even worse than on a standard MP2 task. Performance for 16, 24 and 32 cores runs are 176, 67 and 95espectively. CPU utilization on 24 and 32 cores are about 24-27or this bigger task. Network loading is commonly less than 7-8ŠPeak loads (very short) are about 50ŠThat is the network almost does not work - as well as CPUs.
We have changed such parameter of switch tuning as Link Speed Duplex (from Auto to Full duplex 1000 Mbps) but it has not helped…
As to adapters I am badly guided in these things. I have on all nodes INTEL PWLA 8492 MT 2xUTP 10/100/1000Mb, PCI. I think it is not bad thing or I am not right?
My switches are of average quality - D-Link DGS-1008D/GE 8хUTP 10/100/1000Mb. I try to use your hint related 16- 24-ports switches if I'll find them at somebody (they are rather expensive…). However it seems the reason should be another – network basically sleeps now.
Granovsky has advised me to apply outputs for some run. OK, I do it for MP2 task in the most effective variant. Please, look. At the end of outputs there is any time statistics since the task has been run with an option -prof in a command line. However, I do not know the sense of these values. I've taken the input for this run from Performance section of FF site (Test 3).
If any data are required, I am ready to give them.

Many thanks for your helps!

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On Wed Mar 31 '10 10:54pm, Alexei Popov wrote
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>Hi,

>it seems you are using the benchmark that is simply
>too small for your cluster. If you look here,
>you'll find that it takes ca. 400-500 seconds to complete on 8 cores.

>Actually, with the latest processors Firefly seems to need the
>updated set of benchmarks, at least for parallel runs.

>I'd suggest you to test performance and scalability of your
>particular cluster/setup using job that takes at least 1-2 hours
>to complete on 8 cores running on single node.

>Your nodes are fast, and my guess is you are using 1 Gbit Ethernet?
>This is most likely optimal solution for such a small cluster,
>at least the price/performance ratio is very reasonable.
>However, you need high quality Ethernet adapters and really
>good switch. Formally you need 8-port switch but I doubt
>if a typical 8-port switch will be good enough for your purposes -
>so you can try to experiment with 16 or 24-port models.

>regards,
>Alexei

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[ MP2.zip ] MP2 run on 8-16-24-32 nodes

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