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Subject: Re: [OMPI devel] OpenMPI Performance Problem with Open|SpeedShop
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2009-01-12 13:00:21


On Jan 9, 2009, at 12:39 AM, William Hachfeld wrote:

> Can any of the OpenMPI developers speculate as to possible
> mechanisms by which the ptrace() attachment , signal handler, or
> timer registration and corresponding signal delivery could cause
> large amounts of time to be spent within the "progress" functions of
> the OpenMPI library with an apparent lack of any real progress? Any
> ideas/information would be greatly appreciated.

Hum; interesting. I can't think of any reason why that would be a
problem offhand. The mca_btl_sm_component_progress() function is the
shared memory progression function. opal_progress() and
mca_bml_r2_progress() are likely mainly dispatching off to this
function.

Does OSS interfere with shared memory between processes in any way?
(I'm not enough of a kernel guy to know what the ramifications of
ptrace and whatnot are)

-- 
Jeff Squyres
Cisco Systems