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User Mailing

ICHEC mail #18

Posted: 2006-03-11

Dear ICHEC users,


1. Transition to the full national service
2. Acknowledging ICHEC in your publications
3. Quality of Service (QoS)
4. Scheduling policies (and a few reminders)
5. New compilers (walton)
6. New task farm utility (walton)
7. 2nd User Group Meeting

1 – Transition to the full national service

As indicated in earlier mailings, the transitional service (TS) will come to an end on 31st May 2006. Access will be discontinued for anyone not supported under the Full National Service (FNS). FNS applications have been accepted from 1st February, with a total of 9 Class C and 4 Class B projects already accepted to date (see http://www.ichec.ie/research). A number of measures have been put in place to incite potential applicants to apply early rather than wait until the end of the TS. Thus,

- FNS batch jobs will be granted a better QoS than TS batch jobs, hence benefit from a faster turn-around time.

- resources granted to FNS projects will not be charged until 1st June 2006, so in effect benefiting from the same "free for all" policy as TS projects.

As the Scientific Council will not be able to process a very large number of applications within a short period, we strongly recommend potential PIs to submit their application to the FNS as soon as possible (instead of waiting until May). Failure to do so may result in delays in the review process, and subsequent breaks of access (for late applicants) when the TS is discontinued.

A call for Class A applications will be issued later this month. We strongly encourage anyone thinking about submitting a Class A application to undertake a proper scalability study of their code before submitting their application, as the case for resources must be established beyond doubts.

For further information on how to apply to the full service, see http://www.ichec.ie/full_national_service and carefully read the application guidelines.

2 – Acknowledging ICHEC in your publications

We would appreciate a formal acknowledgement of ICHEC by inclusion in any resulting publications of the following sentence or some variation thereof:

"The authors wish to acknowledge the SFI/HEA Irish Centre for High-End Computing (ICHEC) for the provision of computational facilities and support."

See our FAQ.

We would also appreciate if you could let us know when such publications are being accepted for publication, as this constitutes one of the major metrics by which the scientific impact of ICHEC will be assessed. This list will be kept up-to-date at http://www.ichec.ie/publications

3 – Quality of Service (QoS)

As explained in the User Mailing #16, QoS is now implemented to provide a better turn around time for CosmoGrid users and projects supported under the Full National Service (so far, Class B and C). You will need to include the following line in your PBS scripts in order to benefit from the QoS:

#PBS -W x=QOS:cosmogrid
if you are a CosmoGrid user, or

#PBS -W x=QOS:ClassC
if your project is a class C project, or

#PBS -W x=QOS:ClassB
if your project is a class B project.

4. Scheduling policies (and a few reminders)

We recommend starting using the -A flag in your PBS script from now on. Although accounting will only become effective from 1st June, we are currently testing the accounting software and would therefore benefit from users specifying this flag to stress test the accounting software. The syntax is as follows:

#PBS -A <project_code>

... where <project_code> is your project code. The project code can be found by using the command "groups", e.g.:

jcd@l2cu27:~> groups
ichec science management icphy001 ulo ddt

So in this example the correct syntax is: #PBS -A icphy001

See also http://www.ichec.ie/user_documentation.php#7

Finally a few more reminders:

- you may specify job sizes which are not a power of 2, e.g., you are not restricted to job size 4, 8, 16, etc. but may specify any job size between 4 (minimum) and 128 nodes (maximum). Please do not reserve resources which your simulation will not use!

- please specify sensible maximum run times in your batch script (#PBS -l walltime). Do not systematically specify the maximum (96 hours) unless necessary. There are a number of reasons for providing reasonable estimates: 1. it ensures a smoother operation of the scheduling system (including predictive tools); and 2. should your job hang but fail to free up resources, these resources will remain unavailable for a shorter period.

- please do NOT reserve production CPUs (ProdLoMem and ProdHiMem) for interactive use.

- finally, we would like to remind you of the existence of the qutil utility (see User Mailing #17) - a number of users have been running applications exhibiting rather poor efficiency lately - please check the performance and scalability of your codes before deciding on how many CPUs you intend to run it, as it may run more efficiently on a smaller number of CPUs.

- the use of #PBS –r n (see User Mailing #16) is recommended to avoid the risk of loop submission of failing jobs.

Thanks for your co-operation - other users of the system will appreciate.

5. New compilers (Walton)

The new Gcc4 environment is now available on Walton. This environment can be loaded as a module, e.g.:

module load gcc4

As a reminder, the command "module avail" will list all the modules available for download, and "module list" will list all the modules you have currently loaded in your environment. Not that this release includes a Fortran 95 compiler in addition to the usual C/C++ compilers.

jcd@l2cu27:~> gcc --version
gcc (GCC) 4.2.0 20060131 (experimental)

The most interesting aspect for ICHEC users is probably the availability of a Fortran95 compiler called gfortran, a welcome improvement over the old g77.

jcd@l2cu27:~> gfortran --version
GNU Fortran 95 (GCC) 4.2.0 20060131 (experimental)

6. New task farm utility (Walton)

A new version of the task farm utility has been installed on Walton. Please report any unexpected behaviour to the Helpdesk.

7. 2nd User Group Meeting

The second ICHEC Users Group Meeting will take place on Tuesday 25th April 2006 (11am - 2pm), at the School of Cosmic Physics, Dublin Institute for Advanced Studies, 5 Merrion Square, Dublin 2. Further details will be circulated in the next User Mailing.

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