[IMPORTANT] FERMI budget hours

Dear users,

We would like to remind you that on FERMI machine there are minimum default settings for the number of nodes 

allocated to a single run. 

The minimum bgsize is 64: if you ask less than that, you will  get 64 nodes in any case. If you ask more than 64 and less than 128, they will be round up to 128.

Since each node corresponds to 16 processors, the minimum number of processors allocated for a single run will be 1024,

even if your runjob asks for less resources.

This means that for 1 hour real time, you will use at least 1024 hours of your budget.

Examples:

----- example I

# @ bgsize=64

runjob --np 1024 --ranks-per-node 16 -exe yourcode.x 

---- = 64 nodes allocated, 1024 MPI tasks (16 MPI tasks per node), 1h real time = 1024h budget

----- example II

# @ bgsize=64

runjob --np 512 --ranks-per-node 8  -exe yourcode.x 

---- = 64 nodes allocated, 512 MPI tasks (8 MPI tasks per node), 1h real time = 1024h budget

----- example III

# @ bgsize=128

runjob --np 512 --ranks-per-node 4  -exe yourcode.x 

---- = 128 nodes allocated, 512 MPI tasks (4 MPI tasks per node), 1h real time = 2048h budget

----- example IV

# @ bgsize=64

runjob --np 32 --ranks-per-node 16  -exe yourcode.x 

---- = 64 nodes allocated, 32 MPI tasks (16 MPI tasks per node on 2 nodes, 62 nodes idle), 1h real time = 1024h budget

----- example V

# @ bgsize = 100

runjob --np 1600 --ranks-per-node 16  -exe yourcode.x 

---- = 128 nodes allocated, 1600 MPI tasks (16 MPI tasks per node on 100 nodes, 28 nodes idle), 1h real time = 2048h budget

 ----- example VI

# @ bgsize = 25

runjob --np 25 --ranks-per-node 1  -exe yourcode.x 

---- = 64 nodes allocated, 25 MPI tasks (1 MPI task per node on 25 nodes, 39 nodes idle), 1h real time = 2048h budget

 As you can understand, it is very easy to burn your budget! So, please BE CAREFUL before submitting jobs.

Cross check your inputs and your job scripts, more than once!

When the job is running, you can check detailed info about your job with the command:

$ llq -l jobID

where jobID is in the form fen03.1000.0

In particular you'll be notified about the bgsize you requested and the real bgsize allocated:

example:

BG Size Requested: 2012

BG Size Allocated: 2048

However, in case of doubt, please don't hesitate to contact superc@cineca.it.

Happy computing!

HPC Support Team @ CINECA