Hi Marko - unfortunately, attachments are also removed on this mailing
list. You can send an email directly to me if you would like me to look at
it.
You can specify which host each place is located on most easily by using
X10_HOSTFILE instead of X10_HOSTLIST. If you are running with 48 places,
then you can create a text file with 48 lines, with a hostname on each
line. Place 0 will run on the host specified on the first line, place 1 on
the second line, and so on. This can also be done with a hostlist, but it
will be a very long command line.
Both the hostfile and hostlist wrap, so when you specify only 4 nodes as
per your email below, you should be getting 12 places on each (node001
should have places 0,4,8,12,etc).
Depending on your program, you may get better performance running with 4
places instead of 48, and use async to increase the parallelism within each
place. You may also want to explicitly set the X10_NTHREADS environment
variable to 1 if you're using 48 places, or 12 if using 4 places. Others
on this mailing list may have additional comments on this.
- Ben
From: Marko Kobal <[email protected]>
To: "[email protected]"
<[email protected]>
Date: 08/09/2011 12:35
Subject: Re: [X10-users] runing on multiple places (cluster) with sockets
RT implementation
Hi,
Me again ;)
I have an example (N-body) written to execute in parallel. It works just
fine, scales good on more cores.
However, when I try to run it on more than one machine, more exactly on 4
nodes, I can see that X10 does not properly distributes the load to the
nodes.
I have nodes with 2 Intel processors, 6 cores each, that makes 12 cores per
node, 48 cores per 4 nodes:
export X10_HOSTLIST=node001,node002,node003,node004
export X10_NPLACES=48
I did compile for the sockets RT Implementation:
# x10c++ -x10rt sockets -o nbody.parallel.sockets nbody.parallel.x10
When I execute the program, I can see that processes are spawn through the
4
nodes, however the load is not distributed evenly. On some nodes there are
more than 12 processes running, on some less than 12. This is obviously not
good as some nodes are overloaded (and as such processing is not optimal)
and some are under loaded (that's not one would wish for). See the print
screen from my monitoring software:
(sorry, the picture was embedded wich is obviusly not supported by the
mailing list, I've put it into attachement now)
The usage for X10Laucher says: X10Launcher [-np NUM_OF_PLACES] [-hostlist
HOST1,HOST2,ETC] [-hostfile FILENAME] COMMAND_TO_LAUNCH [ARG1 ARG2 ...] .
so
there is no parameter to set "processes per node" . I would expect
something
similiar as is the "-perhost" parameter in the MPI world. Is there any way
to achieve this with the X10 sockets RT Implementation?
Thanks for help!
Kind regards, Marko Kobal
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