[MPICH] MPD caused major system throughput degration, Redhat ES 4, U2

[chong tan]

I am using 1.0.3.  the situation is very inteesting in
that it only happened on Linux.  the box ran Solaris
10 for a while, and I have never seen that behavior.

Secondly, I just rebooted the box, and the problem has
not show up after 24 hr.

In my opinion, the problem is wacky, in that :
  -  the application showing the throughput degration
did not use MPI at all.
  -  there are 2 CPU, with 2 core each on the system,
there should be rather minor hit as CPU is always
there to run mpd.
  -  240 second out of 620 hit with mpd running is way
too much.

 
tan


--- Ralph Butler <rbutler at mtsu.edu> wrote:

> Are you sure you have the latest release of mpich2. 
> I ask this
> because a long time ago there was a bug in mpd that
> caused excessive
> checking of sockets in the main loop.
> 
> I logged in to each of 3 machines running:
>      Debian Linux
>      Fedora Core 5
>      Mac OS X
> I was the only user on each machine and each
> initially had:
>      load average: 0.00, 0.00, 0.00
> 
> On every host I ran the same job (that took at least
> 124 seconds
> depending on the platform).  I ran the job several
> times, both with
> and without MPD running.  The time never varied by
> no more than
> 0.1 second on a single platform.
> 
> --ralph
> 
> On ThuAug 17, at Thu Aug 17 4:13PM, chong tan wrote:
> 
> > on SUN Ultra 40, 2 Opterons 280, 8G memory.
> > The application does not use mpi at all
> >
> > time application .....
> > 627.007u ....... 99.9% ....
> >
> > if I start mpd before the application:
> >
> > mpd &
> > time application .....
> > 860.365u ........ 99.9% ...
> >
> > If I kill the mpd using mpdallexit, and I rerun
> the
> > application, I get almos the same time.
> >
> > The application is the only one running on the
> box,
> > cause I am still in the process of setting up that
> > box.
> >
> > any suggestion ?
> >
> > tan
> >
> >
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> 


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