Jean Zay: Regulating of computing hours

A project which has obtained hours on Jean Zay has an initial allocation of hours.

This allocation has now been increased by 25% in supplementary hours which can only be used when the machine is under-utilised.

More precisely:

  • As soon as the consumption of a project exceeds 125% of its initial allocation of hours, the project will be blocked and no member will be able to submit work.
  • A priority system based on a fairshare principle allows managing the execution of jobs on the machine in the most equitable way possible between projects. This system takes into account various parameters, including in particular the initial allocation of hours and the hours already consumed (the actual accounting decreases exponentially with time, with a half-life of 14 days).
  • A project that has under-consumed in the recent past (i.e. during the last days or weeks) benefits from a high priority for the execution of its jobs.
  • A project that has over-consumed in the recent past is not blocked: It can continue to submit jobs but with a lower priority. It can, therefore, benefit from cycles available on the target machine due to low load which otherwise would have been lost.
  • To obtain information about the under- or over-consumption of your projects, you can use the following command:
    $ idr_compuse

This priority system maximizes the effective use of machine cycles by:

  • Encouraging projects to use their hours regularly throughout the year in order to benefit from a high priority of execution for a maximum number of hours.
  • In the event of under-utilisation of the machine, allowing projects to either catch up on a delay in consumption or to get ahead despite having a low execution priority with the only hours limit being that of 125% of their initial allocation of hours.

Note that on the supercomputers installed at IDRIS prior to Jean Zay, a mechanism for recuperation of computing hours had been put in place which meant that projects having obtained a large allocation could lose hours in case of under-consumption. On Jean-Zay, this mechanism has been cancelled and replaced by the automatic regulation described above which enables a homogeneous policy between the three national centres.

For any questions about the accounting of computing hours on Jean-Zay, please see here.