Hi,
I use Infiniband(--mca btl openib,self).
I know that waiting allreduce might cause high cpu consumption.
I intended to create such a situation to check system cpu usage
when some processes are kept waiting. I'm afraid that it might
affect execution speed. Indeed, my application (MUMPS base)
Not sure why they would be different, though there are changes to the code, of
course. Would have to dig deep to find out why - perhaps one of the BTL
developers will chime in here. Which transport are you using (Infiniband, TCP,
?)?
As for why the cpu gets consumed, it's that allreduce that is
Hi,
I made my testing program simpler as shown below.
I compared openmpi-1.6.2 and openmpi1.7rc1/4 again
in system cpu usage while some processes wait for
others.
Then, the result is same as reported bofore.
system cpu usage
openmpi-1.6.2 0%
openmpi-1.7rc1 70%
openmpi-1.7
Hi Ralph, thank you for your comment.
I understand what you mean. As you pointed out, I have one process sleep
before finalize. Then, mumps finalize might affect the behavior.
I will remove mumps finalize (and/or initialize) function from my testing
program ant try again on next Monday to make
I'm not sure - just fishing for possible answers. When we see high cpu usage,
it usually occurs during MPI communications - when a process is waiting for a
message to arrive, it polls at a high rate to keep the latency as low as
possible. Since you have one process "sleep" before calling the fin
Hi Ralph,
do you really mean "MUMPS finalize"? I don't think it has much relation
with
this behavior?
Anyway, I'm just a mumps user. I have to ask mumps developers about what
MUMPS
initailize and finalize does.
Regartds,
tmishima
> Out of curiosity, what does MUMPS finalize do? Does it send a
Out of curiosity, what does MUMPS finalize do? Does it send a message or do a
barrier operation?
On Oct 25, 2012, at 5:53 PM, tmish...@jcity.maeda.co.jp wrote:
>
>
> Hi,
>
> I find that system CPU time of openmpi-1.7rc1 is quite different with
> that of openmpi-1.6.2 as shown in the attached
