[mpich-discuss] hydra_pmi_proxy using 100% CPU

[Pavan Balaji]

On 01/21/2011 12:42 AM, Colin Hercus wrote:
> First apologies for calling you Pravind in earlier emails. Pravind is a
> past colleague and I was in automatic mode :)

Heh :-). I was wondering who Pravind was.

> 1. Is it possible to use MPI IO to write to stdout? I couldn't see how
> to do this.

No, I meant to a file.

> 2. If I don't use MPI IO and stick to writing to stdout with fwrite() is
> it better to do a) Send from slave to master and then fwrite in master
> or b) write to stdout in the slaves.

All stdout from all processes is always funnelled through the master.

In general stdout of more than a few hundred bytes is a bad idea. 
Process managers do not optimize for large amounts of stdout, but rather 
focus on convenience of stdout formatting. So they might parse the 
stdout to find new line characters, add prefixes, etc. This is obviously 
terrible if you are writing 1GB of data.

  -- Pavan

-- 
Pavan Balaji
http://www.mcs.anl.gov/~balaji