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From: Neeraj Chourasia (neeraj_ch1_at_[hidden])
Date: 2007-10-12 08:38:06


Yes, the buffer was being re-used. No we didnt try to benchmark it with netpipe and other stuffs. But the program was pretty simple. Do you think, I need to test it with bigger chunks (>8MB) for communication.?We also tried manipulating eager_limit and min_rdma_sze, but no success.NeerajOn Fri, 12 Oct 2007 13:00:10 +0200 Open MPI Users wrote Hello, > The code was pretty simple. I was trying to send 8MB data from one > rank to other in a loop(say 1000 iterations). And then i was taking the > average of time taken and was calculating the bandwidth. > > The above logic i tried with both mpirun-with-mca-parameters and without > any parameters. And to my surprise, the performance was degrading when i > was trying to manipulate. That sounds strange. So did you re-use the communication buffers? Did you try to run some existing benchmarks like Netpipe [1], IMB or Netgauge [2]? > Now I have another question in mind. Is it possible to have IB Hardware
  > Multicast implementation in OpenMPI? I have gone through the > issues/challenges for the same, but also read couple of people who have > successfully done it for Ethernet/Giga-bit Ethernet and IPoIB ofcourse in > experimental stage. Actually i want to contribute for it in OpenMPI and > need the help for the same. As far as I know, there are two groups/people working on this. Andy Friedley implements a \"traditional\" ACK based approach (like the one that the OSU folks published about some time ago) and I implemented a new idea for extreme scale (see \"A practically constant-time MPI Broadcast Algorithm for large-scale InfiniBand Clusters with Multicast\" [3]). I know that my version is still unstable and has some problems. But I\'m working on this. Best, Torsten [1]: http://www.scl.ameslab.gov/netpipe/ [2]: http://www.unixer.de/research/netgauge/ [3]: https://www.unixer.de/publications/#hoefler-cac07 -- bash$ :(){ :|:&};: ---------------------
 
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