[Lustre-discuss] Limits for o2ib lnet network numbers

Liang Zhen liang at whamcloud.com
Wed Aug 8 07:38:57 PDT 2012

Hi, LNet reserved 32 bits for network number, so you can choose a very large network number if only have a few networks, but really create many networks will have some issues:
- o2iblnd will pre-allocate memory resources for each network, so it will consume a lot of memory
- Main stream LNet will have performance issue if there're many networks, for example, hundreds, although it's not difficult to fix this.


On Aug 8, 2012, at 10:23 PM, Rick Mohr wrote:

> I was curious what limitations exist for o2ib network numbers.  Most of
> the time I am dealing with o2ib0, o2ib1, etc.  As as experiment, I tried
> configuring a machine with o2ib1000, and that seemed to be OK.  I
> figured there must be some limit on how large the network number can
> get, but after doing some searching, I have been unable to find any docs
> that specify a limit.  Does any know what the max network number is?
> -- 
> Rick Mohr
> HPC Systems Administrator
> National Institute for Computational Sciences
> http://www.nics.tennessee.edu/
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