Re: Running with more that 1/2 CPU's -- June 24, 2013

Hi,

The only limit is the amount of RAM in your system.  I have no idea
how much memory one relax instance running a relaxation dispersion
analysis would take up.  But if you have enough you could run 10
instances of relax.  If these datasets are not part of the same
analysis then you would need to run relax 10 times separately anyway,
so in such a case the multi-processor framework from Gary Thompson
will not be of use.  The multi-processor framework would massively
speed up the process if you could only run one instance of relax at a
time.  I hope this answers your question.

Regards,

Edward


On 24 June 2013 13:24, Troels Emtekær Linnet <tlinnet@xxxxxxxxx> wrote:

Is there a limit to how many program instances you can require of relax?

If you have for example 10 different datasets you want to be analysed,
would a work-around be to use calls to a lot of relax programs ?

Is there any shared memory / temporary directories which prevent this?

Best
Troels Emtekær Linnet


2013/6/7 Edward d'Auvergne <edward@xxxxxxxxxxxxx>


Hi,

If you have OpenMPI and mpi4py installed, then you have access to Gary
Thompson's multi-processor framework for MPI parallelisation.  However
the code in relax must be written to support this.  This is the case
for the model-free analysis, in which case Gary has achieved near
perfect scaling efficiency:

https://mail.gna.org/public/relax-devel/2007-05/msg00000.html

However for the relaxation dispersion branch, no parallelisation has
been attempted, neither in the original code from Sebastian Morin or
the recent modifications by myself.  This is not a simple task and
will take a lot of effort to implement.  If this is to be implemented
one day, I would suggest parallelising at the level of the spin
clusters.

Also note that it is often quite hard to achieve good scaling
efficiency and often the first attempts will just make the code
slower, even on a 1024 node cluster, due to the bottleneck of data
transfer between the nodes.  The parallelisation will also require 10
times as much code to be written to do the same thing as
non-parallised code, and debugging is much more difficult.  So while
it is an option, I wouldn't hold your breath for this feature.  Of
course unless you have the courage to tackle such a problem yourself.

Regards,

Edward




On 7 June 2013 12:24, Troels Emtekær Linnet <tlinnet@xxxxxxxxx> wrote:

Hi.

I have access to a computer with 24 CPU's, and want to speed things up.

Architecture:          x86_64
CPU op-mode(s):        32-bit, 64-bit
Byte Order:            Little Endian
CPU(s):                24
On-line CPU(s) list:   0-23
Thread(s) per core:    2
Core(s) per socket:    6
Socket(s):             2
NUMA node(s):          2
Vendor ID:             GenuineIntel
CPU family:            6
Model:                 44
Stepping:              2
CPU MHz:               2394.136
BogoMIPS:              4787.82
Virtualization:        VT-x
L1d cache:             32K
L1i cache:             32K
L2 cache:              256K
L3 cache:              12288K
NUMA node0 CPU(s):     0,2,4,6,8,10,12,14,16,18,20,22
NUMA node1 CPU(s):     1,3,5,7,9,11,13,15,17,19,21,23

I have been looking at:
http://www.nmr-relax.com/manual/Usage_multi_processor.html

This says, that you need mpi installed.

Is it possible to run relax_disp in GUI mode with more than 1/2
processors?

Best


Troels Emtekær Linnet

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Re: Running with more that 1/2 CPU's

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