[mpich-discuss] Hydra binding questions

[Jain, Rohit]

Hi,

I have been experimenting with different binding method for our application with Hydra, and trying to find best performing method to set as default.
I have few questions:


1)      Is there any debug output by Hydra, which tells particular core/processor binding (core numbers) associated with a process? We can use this info to see variation of binding methods on different architectures.

2)      We expected cpu:sockets and cache:l3 binding to behave same on an AMD box due to its layout (2 processors with 6 cores each). But, there is difference in performance of about 10%. Is that expected? Again, any information on binding will help, currently it is black box for us of what Hydra does.

3)      While running on AMD Opteron machine, I monitored 'top' as application was running. I found that processes are shuffling between different cores during the run. Is that expected, as processes are bind to a particular core? I also noticed it on Intel machine, but happening less frequently.

4)      We currently use numactl/taskset to set affinity with mpd. Does hydra allow specifying affinity with numactl/taskset, instead of -binding?

5)      What parameter does hydra read from machine to determines binding? /proc/cpuinfo or more?


Regards,
Rohit

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/mpich-discuss/attachments/20110801/e0947f01/attachment.htm>