Charm++ parallel programming system

[Abhinav Bhatele <bhatele AT illinoisalumni.org>]

Hi Justin,

NAMD uses a specialized load balancer. If you wanted this for NAMD, you would have to modify NAMD source code. The struct processorInfo in elements.h is used. You'll need to add a pe_speed variable there.

Then you will need to adapt the load balancers in NAMD (the source for which is in TorusLB.C and RefineTorusLB.C) to respect pe_speed's and assign load accordingly.

We can provide more assistance depending on what you want to do.

- Abhinav

On Wed, Oct 12, 2011 at 12:26 PM, Justin Luitjens <jluitjens AT nvidia.com> wrote:

Yes I am working in NAMD.  I found the function LDProcessorSpeed() in the charm framework.  This looks to be a place where I could edit charm to do what I want but it would be better if there were an API to do this.  Thank you for your help on this.  In our case the processor speed that is measured will be the same, but we have one process on each node that is specialized.  We essentially want that process to be assigned a reduced amount of work so that it has more time for other activities.

 

Justin

 

From: Kale, Laxmikant V [mailto:kale AT illinois.edu]
Sent: Wednesday, October 12, 2011 11:58 AM
To: Justin Luitjens; charm AT cs.uiuc.edu
Subject: Re: [charm] Heterogenous Load Balancing

 

Yes, it is very much possible..  (Its been in the deign of charm load balancers for a long time.)

 

pe_speed is the correct variable. However, you also need top use a balancer (strategy) that pays attention to this variable.

Also, this variable is currently set by running some standard loop at the beginning of the computation. So, make sure its correctly normalized by printing the value for all (or multiple) processors,

 

Are you doing this for NAMD? There may be a more specialized answer for namd load balancer.

 

-- 

Laxmikant (Sanjay) Kale         http://charm.cs.uiuc.edu

Professor, Computer Science     kale AT illinois.edu

201 N. Goodwin Avenue           Ph:  (217) 244-0094

Urbana, IL  61801-2302          FAX: (217) 265-6582

 

On 10/12/11 1:23 PM, "Justin Luitjens" <jluitjens AT nvidia.com> wrote:

 

Hi,

 

I’ve been digging into the load balancer and it seems that if we were able to set the pe_speed for each process we would be able to accomplish this.  Is there an API available to set the CPU speed manually?

 

Thanks,

Justin

 

From: charm-bounces AT cs.uiuc.edu [mailto:charm-bounces AT cs.uiuc.edu] On Behalf Of Justin Luitjens
Sent: Wednesday, October 12, 2011 8:23 AM
To: charm AT cs.uiuc.edu
Subject: [charm] Heterogenous Load Balancing

 

Hello,

 

Is it possible to specify processor weights in charm for heterogenous systems or does it assume homogenous processors?  We would like to set a certain subset of PE’s so that work less work is distributed to them.  Is this possible?

 

Thanks,

Justin

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--
Abhinav Bhatele, people.llnl.gov/bhatele1
Center for Applied Scientific Computing, Lawrence Livermore National Laboratory