KAUST Supercomputing Laboratory Newsletter 25th November 2015

Shaheen II Filesystem

We are pleased to confirm that the problem affecting the filesystem availability has been resolved and the system is fully available for use.

Maintenance Session 1st December 2015

The next maintenance session on Shaheen II will be on Tuesday 1st December from 12:00 until 17:00.

XSEDE HPC Workshop: OpenACC

The registration page for the XSEDE HPC Monthly Workshop Series - December 3 - OpenACC session is up.

The portal registration page can be found here:

https://portal.xsede.org/course-calendar/-/training-user/class/450/session/855

If there is enough interest, KSL will investigate the possibility of streaming this course live in the Library computer room on Thursday 3rd of December in the evening starting at 6pm.

Neser Last Day of Service

Please note this system will be decommissioned in January, the last day that any job will be able to run is 31st December 2015.

Tip of the Week:Using huge pages for optimization

Huge pages are virtual memory pages which are bigger than the default base page size of 4KB. Huge pages can improve memory performance for common access patterns on large data sets. Huge pages also increase the maximum size of data and text in a program accessible by the high speed network.

The Cray Aries interconnect can map more pages using fewer resources meaning communications may be faster. Your code may run with fewer TLB misses (hence faster) however, your code may load extra data and so run slower.

Only way to know is by experimentation. Use modules to change default page sizes (man intro_hugepages for more information). module load craype-hugepages2M and craype-hugepag8M are most commonly successfully on Cray XC.

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