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I have a cluster with Gigabit ethernet network. I don't need more bandwidth but the latency is important. ping shows that the latency between nodes are about 100 microseconds. Is there a way to have lower latency with this hardware?
mohammadh montazeri
Posted 2016-06-17T13:36:43.793
Reputation: 131
Is the cluster in the same physical place? – NIZ – 2016-06-17T13:42:34.797
I think you mean milliseconds? If yes, then it is quite slow. If you really mean microseconds, I don't see any problem. – TJJ – 2016-06-17T13:52:43.310
@NIZ: Yes. All the server, nodes and consoles are within 10 meters. So cables are not long. – mohammadh montazeri – 2016-06-17T13:55:19.140
@TJJ: 100 microseconds is good for usual networks, but is so bad for HPC clusters which should be in the order of 10 microseconds – mohammadh montazeri – 2016-06-17T13:57:50.740
Are you sure? In my network I typically reach average 1000 microseconds between nodes. So I would consider 100 microseconds on usual network exceptionally good already. – TJJ – 2016-06-17T14:10:32.430
I think @TJJ is right :) Sorry missed the "microseconds" part – NIZ – 2016-06-17T14:15:58.220
@TJJ : 0.1 milisecond=100 microsecond is typical for gigabit ethernet networks and if you have 1000 microseconds latency in gigabit, your network is so slow!!! but as I said, HPCs should have less latency. 10GB ethernet has about 1 microsecond latency, but it needs hardware upgrade and is expensive! – mohammadh montazeri – 2016-06-17T14:27:07.473
@mohammadh montazeri Ok. I just wanted to be sure you haven't made a mistake. Actually, I was also partly wrong because I gave my ping time as PC-to-PC, not node-to-node. So the switch will of course increase the time. So I guess yes, with expensive super fast networking technology you should be able to get lower latencies :) – TJJ – 2016-06-17T14:40:00.310