On Jul 11, 2009, at 11:13 PM, Klymak Jody wrote:
Hi Vitorio,
On 11-Jul-09, at 8:40 PM, Luis Vitorio Cargnini wrote:
did you saw that, maybe, just maybe using:
xserve01.local slots=8 max-slots=8
xserve02.local slots=8 max-slots=8
xserve03.local slots=8 max-slots=8
xserve04.local slots=8 max-slots=8
it can set the number of process specifically for each node, the
"slots" does this setting the configuration of slots per each node,
try it with the old conf of Xgrid and also test with your new Xgrid
conf.
As per Ralph's message, the xgrid launcher ignores --hostfiles...
Further, "max_slots=2" is the same as "slots=2 max_slots=2"
according to the man page.
Xgrid does have a somewhat convoluted, and poorly documented, method
of directing jobs to specified machines. Its called Scoreboard and
it allows the scheduler to query each machine with a script that
gathers info about the machine and compute a "score". Nodes with
the highest score get the job. However, how one would implement
that using openMPI is unclear to me. Does openMPI have the
capability of passing arbitrary arguments to the resource managers?
Assuming that Scoreboard is appropriately licensed (i.e., is not
licensed under GPL, but preferably something like FreeBSD), and that
it has an accessible API, then we can link against it when in that
environment and interact any way we desire - including asking
Scoreboard for its recommended list of nodes.
Thanks, Jody
Regards.
Vitorio.
Le 09-07-11 à 18:11, Klymak Jody a écrit :
If anyone else is using xgrid, there is a mechanism to limit the
processes per machine:
sudo defaults write /Library/Preferences/com.apple.xgrid.agent
MaximumTaskCount 8
on each of the nodes and then restarting xgrid tells the
controller to only send 8 processes to that node. For now that is
fine solution for my need. I'll try and figure out how to specify
hosts via xgrid and get back to the list...
Thanks for everyone's help,
Cheers, Jody
On 11-Jul-09, at 12:42 PM, Ralph Castain wrote:
Looking at the code, you are correct in that the Xgrid launcher
is ignoring hostfiles. I'll have to look at it to determine how
to correct that situation - I didn't write that code, nor do I
have a way to test any changes I might make to it.
For now, though, if you add --bynode to your command line, you
should get the layout you want. I'm not sure you'll get the rank
layout you'll want, though...or if that is important to what you
are doing.
Ralph
On Jul 11, 2009, at 1:18 PM, Klymak Jody wrote:
Hi Vitorio,
Thanks for getting back to me! My hostfile is
xserve01.local max-slots=8
xserve02.local max-slots=8
xserve03.local max-slots=8
xserve04.local max-slots=8
I've now checked, and this seems to work fine just using ssh.
i.e. if I turn off the Xgrid queue manager I can submit jobs
manually to the appropriate nodes using --hosts.
However, I'd really like to use Xgrid as my queue manager as it
is already set up (though I'll happily take hints on how to set
up other queue managers on an OS X cluster).
So you have 4 nodes each one with 2 processors, each processor
4-core - quad-core.
So you have capacity for 32 process in parallel.
The new Xeon chips designate 2-processes per core, though at a
reduced clock rate. This means that Xgrid believes I have 16
processors/node. For large jobs I expect that to be useful, but
for my more modest jobs I really only want 8 processes/node.
It appears that the default way xgrid assigns the jobs is to
fill all 16 slots on one node before moving to the next.
OpenMPI doesn't appear to look at the hostfile configuration
when using Xgrid, so it makes it hard for me to deprecate this
behaviour.
Thanks, Jody
I think that only using the hostfile is enough is how I use. If
you to specify a specific host or a different sequence, the
mpirun will obey the host sequence in your hostfile to start
the process, also can you put how you configured your host
files ? I'm asking this because you should have something like:
# This is an example hostfile. Comments begin with
# #
# The following node is a single processor machine:
foo.example.com
# The following node is a dual-processor machine:
bar.example.com slots=2
# The following node is a quad-processor machine, and we
absolutely
# want to disallow over-subscribing it:
yow.example.com slots=4 max-slots=4
so in your case like mine you should have something like:
your.hostname.domain slots=8 max-slots=8 # for each node
I hope this will help you.
Regards.
Vitorio.
Le 09-07-11 à 10:56, Klymak Jody a écrit :
Hi all,
Sorry in advance if these are naive questions - I'm not
experienced in running a grid...
I'm using openMPI on 4 duo Quad-core Xeon xserves. The 8
cores mimic 16 cores and show up in xgrid as each agent having
16 processors. However, the processing speed goes down as the
used processors exceeds 8, so if possible I'd prefer to not
have more than 8 processors working on each machine at a time.
Unfortunately, if I submit a 16-processor job to xgrid it all
goes to "xserve03". Or even worse, it does so if I submit two
separate 8-processor jobs. Is there anyway to steer jobs to
less-busy agents?
I tried making a hostfile and then specifying the host, but I
get:
/usr/local/openmpi/bin/mpirun -n 8 --hostfile hostfile --host
xserve01.local ../build/mitgcmuv
Some of the requested hosts are not included in the current
allocation for the
application:
../build/mitgcmuv
The requested hosts were:
xserve01.local
so I assume --host doesn't work with xgrid?
Is a reasonable alternative to simply not use xgrid and rely
on ssh?
Thanks, Jody
--
Jody Klymak
http://web.uvic.ca/~jklymak
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