Service Unit Policies

Service Unit Definition

The heterogeneous architecture of the Frank shared hardware means that some CPUs will be more valuable to different types of jobs. For example, a Westmere node has 12 cores at 2.7 GHz and 4 GB/core, which is connected to other Westmere nodes by Inifiband. These nodes seem well suited to large distributed memory calculations that can efficiently use multiple nodes in parallel. In contrast, a Mangy-cour node has a slower CPU speed of 2.1 GHz with 48 cores and only 2.75 GB per core and these nodes are connected by slower Gigabit Ethernet. These nodes would seem to be more suited to shared memory calculations where most or all of the cores can be efficiently utilized. Using published Linpack results, the Sandy Bridge processor is expected to out perform the Westmere processor by about a factor of 2. In our own testing, we have found that the Sandy Bridge processor improves on the Westmere processor by about a factor of 1.5.

For the purpose of fair charging of cpu-hours for several types of jobs a service unit (SU) will be defined as a function of CPU type, CPUs consumed and total wall time.

SU = wall-time * cpu-scale * ncpus

The scale factors are

Magny Cours Interlagos Westmere Sandy Bridge GPUs
0.5 0.75 1.0 1.5 8.0

Example jobs

  1. A 2 Magny Cour CPU job that ran for 4 hours would be charged 4 service units
  2. A 60 Westmere CPU job that ran for 72 hours would be charged 4320 service units
  3. A 2-GPU job that ran for 1 day would be charged 384 service units
  • Note that GPU jobs are not charged for CPU-hour utilization, but only for GPU-hour utilization.

Please review the System Architecture for CPU type definitions.

Service Unit Allocations

Service units are allocated on a per group basis. For all groups given access to Frank, the first 10,000 service units utilized per year are free. An allocation request is required to gain access. Service units may be used for Shared Memory or Distributed Memory jobs on Frank. Each year, once the 10,000 service units have been spent, more service units may be acquired through participation in one of the SaM Investment Options described elsewhere. Service unit charges are not applied to jobs that run on the Fermi queues.

Service Units beyond the yearly 10,000 can be purchased at the rate of $0.01/SU. Please contact samhelp@pitt.edu for more information.

Allocations are maintained by the GOLD allocation manager. When a job is submitted, MOAB will check the GOLD account to determine if sufficient funds exist for the full service units specified in the submission script before the job can start. If sufficient funds exist, a reservation for the full amount is made in the name of user, but upon completion only the utilized service units will be debited from the account. To view the current balance on frank run

mybalance -h

Follow this link for a description of commands to run to determine more detailed information about your allocation and charges that have been made.