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Calculating the distribution of queue times

 

Given the state of a system -- the number of jobs currently running, their ages and their cluster sizes -- we can use the CLM to estimate the wait time until a given cluster size, n, is available.

We describe the state of the machine at the time of an arrival as follows: there are p jobs running, with ages tex2html_wrap_inline658 and cluster sizes tex2html_wrap_inline656 (in other words, the ith job has been running on tex2html_wrap_inline656 processors for tex2html_wrap_inline658 seconds). We would like to predict Q(n'), the time until n' additional processors become available, where tex2html_wrap_inline664 and tex2html_wrap_inline666 is the number of free processors.

In the next two sections we will present ways to estimate the median and mean of Q(n'). Then we will use these values to predict wait times during a trace-driven simulation.





Allen Downey
Fri May 30 15:09:42 PDT 1997