Patrick,
by the way, this will work when running on a single node.
i do not know what will happen when you run on multiple node ...
since there is no OAR integration in openmpi, i guess you are using ssh
to start orted on the remote nodes
(unless you instructed ompi to use an OARified version of ssh)
my concern is the remote orted might not run within the cpuset that was
created by OAR for this job,
so you might end up using all the cores on the remote nodes.
please let us know how that works for you
Cheers,
Gilles
On 9/18/2015 5:02 PM, Gilles Gouaillardet wrote:
Patrick,
i just filled PR 586 https://github.com/open-mpi/ompi-release/pull/586
for the v1.10 series
this is only a three line patch.
could you please give it a try ?
Cheers,
Gilles
On 9/18/2015 4:54 PM, Patrick Begou wrote:
Ralph Castain wrote:
As I said, if you don’t provide an explicit slot count in your
hostfile, we default to allowing oversubscription. We don’t have OAR
integration in OMPI, and so mpirun isn’t recognizing that you are
running under a resource manager - it thinks this is just being
controlled by a hostfile.
That's look strange for me is that in this case (default)
oversubscription is allowed for the number of core of one cpu (8),
not the number of cores available in the node (16) or unlimited...
If you want us to error out on oversubscription, you can either add
the flag you identified, or simply change your hostfile to:
frog53 slots=4
Either will work.
This syntax in the host file doesn't change anything to the
oversuscribing problem. It is still allowed with the same maximum
amount of processes for this test case:
[begou@frog7 MPI_TESTS]$ mpirun -np 8 *--hostfile frog7.txt*
--bind-to core ./location.exe|grep 'thread is now running on PU' |sort
(process 0) thread is now running on PU logical index 0 (OS/physical
index 0) on system frog7
(process 1) thread is now running on PU logical index 2 (OS/physical
index 6) on system frog7
(process 2) thread is now running on PU logical index 0 (OS/physical
index 0) on system frog7
(process 3) thread is now running on PU logical index 2 (OS/physical
index 6) on system frog7
(process 4) thread is now running on PU logical index 3 (OS/physical
index 7) on system frog7
(process 5) thread is now running on PU logical index 1 (OS/physical
index 5) on system frog7
(process 6) thread is now running on PU logical index 2 (OS/physical
index 6) on system frog7
(process 7) thread is now running on PU logical index 3 (OS/physical
index 7) on system frog7
[begou@frog7 MPI_TESTS]$ *cat frog7.txt*
frog7 slots=4
Patrick
On Sep 16, 2015, at 1:00 AM, Patrick Begou
<patrick.be...@legi.grenoble-inp.fr
<mailto:patrick.be...@legi.grenoble-inp.fr>> wrote:
Thanks all for your answers, I've added some details about the
tests I have run. See below.
Ralph Castain wrote:
Not precisely correct. It depends on the environment.
If there is a resource manager allocating nodes, or you provide a
hostfile that specifies the number of slots on the nodes, or you
use -host, then we default to no-oversubscribe.
I'm using a batch scheduler (OAR).
# cat /dev/cpuset/oar/begou_7955553/cpuset.cpus
4-7
So 4 cores allowed. Nodes have two height cores cpus.
Node file contains:
# cat $OAR_NODEFILE
frog53
frog53
frog53
frog53
# mpirun --hostfile $OAR_NODEFILE -bind-to core location.exe
is okay (my test code show one process on each core)
(process 3) thread is now running on PU logical index 1
(OS/physical index 5) on system frog53
(process 0) thread is now running on PU logical index 3
(OS/physical index 7) on system frog53
(process 1) thread is now running on PU logical index 0
(OS/physical index 4) on system frog53
(process 2) thread is now running on PU logical index 2
(OS/physical index 6) on system frog53
# mpirun -np 5 --hostfile $OAR_NODEFILE -bind-to core location.exe
oversuscribe with:
(process 0) thread is now running on PU logical index 3
(OS/physical index 7) on system frog53
(process 1) thread is now running on PU logical index 1
(OS/physical index 5) on system frog53
(*process 3*) thread is now running on PU logical index*2
(OS/physical index 6)*on system frog53
(process 4) thread is now running on PU logical index 0
(OS/physical index 4) on system frog53
(*process 2*) thread is now running on PU logical index*2
(OS/physical index 6)*on system frog53
This is not allowed with OpenMPI 1.7.3
I can increase until the maximul core number of this first pocessor
(8 cores)
# mpirun -np 8 --hostfile $OAR_NODEFILE -bind-to core location.exe
|grep 'thread is now running on PU'
(process 5) thread is now running on PU logical index 1
(OS/physical index 5) on system frog53
(process 7) thread is now running on PU logical index 3
(OS/physical index 7) on system frog53
(process 4) thread is now running on PU logical index 0
(OS/physical index 4) on system frog53
(process 6) thread is now running on PU logical index 2
(OS/physical index 6) on system frog53
(process 2) thread is now running on PU logical index 1
(OS/physical index 5) on system frog53
(process 0) thread is now running on PU logical index 2
(OS/physical index 6) on system frog53
(process 1) thread is now running on PU logical index 0
(OS/physical index 4) on system frog53
(process 3) thread is now running on PU logical index 0
(OS/physical index 4) on system frog53
But I cannot overload more than the 8 cores (max core number of one
cpu).
#mpirun -np 9 --hostfile $OAR_NODEFILE -bind-to core location.exe
A request was made to bind to that would result in binding more
processes than cpus on a resource:
Bind to: CORE
Node: frog53
#processes: 2
#cpus: 1
You can override this protection by adding the "overload-allowed"
option to your binding directive.
Now if I add*--nooversubscribe*the problem doesn't exist anymore
(no more than 4 processes, one on each core). So looks like if
default behavior would be a nooversuscribe on cores number of the
socket ???
Again, with 1.7.3 this problem doesn't occur at all.
Patrick
If you provide a hostfile that doesn’t specify slots, then we use
the number of cores we find on each node, and we allow
oversubscription.
What is being described sounds like more of a bug than an intended
feature. I’d need to know more about it, though, to be sure. Can
you tell me how you are specifying this cpuset?
On Sep 15, 2015, at 4:44 PM, Matt Thompson <fort...@gmail.com
<mailto:fort...@gmail.com>> wrote:
Looking at the Open MPI 1.10.0 man page:
https://www.open-mpi.org/doc/v1.10/man1/mpirun.1.php
it looks like perhaps -oversubscribe (which was an option) is now
the default behavior. Instead we have:
*-nooversubscribe, --nooversubscribe*
Do not oversubscribe any nodes; error (without starting any
processes) if the requested number of processes would cause
oversubscription. This option implicitly sets "max_slots"
equal to the "slots" value for each node.
It also looks like -map-by has a way to implement it as well (see
man page).
Thanks for letting me/us know about this. On a system of mine I
sort of depend on the -nooversubscribe behavior!
Matt
On Tue, Sep 15, 2015 at 11:17 AM, Patrick
Begou<patrick.be...@legi.grenoble-inp.fr>wrote:
Hi,
I'm runing OpenMPI 1.10.0 built with Intel 2015 compilers on
a Bullx System.
I've some troubles with the bind-to core option when using
cpuset.
If the cpuset is less than all the cores of a cpu (ex: 4
cores allowed on a 8 cores cpus) OpenMPI 1.10.0 allows to
overload these cores until the maximum number of cores of
the cpu.
With this config and because the cpuset only allows 4 cores,
I can reach 2 processes/core if I use:
mpirun -np 8 --bind-to core my_application
OpenMPI 1.7.3 doesn't show the problem with the same situation:
mpirun -np 8 --bind-to-core my_application
returns:
/A request was made to bind to that would result in binding
more//
//processes than cpus on a resource/
and that's okay of course.
Is there a way to avoid this oveloading with OpenMPI 1.10.0 ?
Thanks
Patrick
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