Review Board 2.0.15

Stats: Allow backing up and restoring of stats which is needed for SMARTS

Review Request #56 - Created July 9, 2010 and updated

Timothy Jones
Stats: Allow backing up and restoring of stats which is needed for SMARTS

Posted (July 10, 2010, 11:47 p.m.)
Can you describe exactly how this is used?  I'm assuming that when you're in a sampling period, that you take stats normally, then before you fast forward, you save to backup(), you then continue to take stats in the primary and when you're done, you restore() and throw away the stats during fast forward?  That about right? This sounds like a subset of the "bin" feature that I took out of the stats package several years ago.

Anyway, I have a ton of changes to the stats package outstanding, so I need to think about how this impacts that.  I also have one other question, how often do you switch from primary to backup?

  1. Ok, your description is basically correct.  SMARTS has three phases: functional warming, detailed warming and measurement.  We gather statistics that we want during the measurement phase.  At the end (before draining the CPU) we take a backup and, as you say, stats continue to be gathered during functional warming and detailed warming.  Then, right before we start measurement again, we restore from the backup.
    Roughly speaking, you need around 8,000 measurement phases to accurately characterise each benchmark, with one backup and one restore for each.