Guidelines for the use of TCM's computers

The majority of the computers in TCM have been purchased from grants held by the group, rather than individuals. It would thus seem logical that those machines are available for the whole group to use.

However, past experience suggests that a few firm guidelines need to exist to ensure that people continue to live, and compute, in harmony. Two points must be addressed.

Firstly, to ensure that the person using the computer as a console enjoys reasonable interactive performance, at least 3GB of memory should be left for his use, and all CPU-intensive remote jobs on group-owned computers should be run at a nice value of at least 15. It would seem reasonable that long-running, backgrounded, CPU-intensive local jobs be treated in a similar fashion. A job which does very large amounts of I/O may also be inappropriate for running on a machine which someone is using as a console: Linux's handling of I/O is still far from ideal. If a background job is causing a machine to produce a noticable delay in responding to keystrokes, or to change focus, it is inappropriate.

Secondly, to ensure fair sharing of resources, no individual should have jobs running on more than eight computers simultaneously (we have about three dozen computers worth running jobs on). The idea that an idle computer is a wasted computer is fallacious. An idle computer is a resource that someone can use, and if no computers are idle, there are no resources available to anyone. Many jobs are now too large for multiple jobs per computer to be practical in general.

Finally, to ensure that there are large machines available for interactive and short jobs, including compilations, the two machines in the public computer room, pc27 and pc52, are limited to jobs of no more than five hours of CPU time. This is not an invitation to chain such jobs with scripts.

I (MJR) do not propose to spend much time (any time) looking for people breaking these rules. However, if someone draws my attention to a breach, I am likely to kill twice as many jobs as would be necessary to restore the individual in breach to being within the rules again. This to ensure that people do not gain from breaking the rules, and therefore that I am not disturbed too often.