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BNL Statistics: user profile |
This graph shows how many users are actively using the scheduler. We estimate our userbase in two ways: one optimistic and the other pessimistic. The optimistic estimate assumes that once a user tries the scheduler, he is always going to use it. The pessimistic estimate assumes that users are not going to use the scheduler again after their last use.
The real curve is somewhere in between. More details are given later.
WARNING: this graph seems not to be self-evident to most people. Please read CAREFULLY the explanation at the end of the page.
For a single user, the pessimistic graph would look like a combination of two step function: from 0 to 1 at the time of first use; from 1 to 0 at the time of last use. The total graph is the sum of all the single user graphs.
By definition, then, the pessimistic graph starts from 0 and ends in 0. There is nothing wrong with the graph, or the scheduler: it is supposed to go down at the current day. It is supposed to go to 0 for the following day, because by definition nobody has yet used the scheduler tomorrow, but you don't see that.
The pessimistic graph tells us when the users stop using the scheduler, but it is very conservative. In fact, most user will stop using the scheduler simply because they don't have any job to submit. It takes understanding of the user behavior to interpret correctly this graph.
Notes
The scheduler was deployed at BNL in September 2002, but statistics report was added in the middle of January 2003. Between January 2003 and April 2003 scheduler statistics for big job requests (> ~20 jobs) weren't reported. At PDSF the statistics start more or less at the same time the scheduler was first deployed.
In general, spikes on the pessimistic graph can represent users that tried the scheduler once, and didn't continue using it. It can also mean that they kept using the scheduler at PDSF. If the spike is between January and April 2003, it can also mean that they started submitting bigger requests, and those didn't get recorded (see above).
Levente Hajdu - page was last modified