I have a question on the object life cycles defined in the PolyMix 4
workload. I'm trying to understand how many objects are expected to be
modified during the normal run of the benchmark (which is ~12 hours, if I
remember correctly).
Clearly, none of the olcStatic objects will change. For olcOther, we
expect very few to change (1/365 will have a cycle time of 1 day. As the
variance is 50%, a small fraction may change within 12 hours.)
The content type that changes most frequently is olcHTML. This has a
lognormal distribution with mean 7 days and sd 1 day. To understand what
that meant, I followed the polygraph code's method of computing aMu and
aSigmaSq from mean and sd. I plugged aMu and sqrt(aSigmaSq) into Matlab's
lognpdf function. From this, it seems that the minimum cycle time for
logn(7 days, 1 day) is 4 days. Factoring in the 33% variation, I figure
that the minimum time for an HTML object to change is ~2.7 days.
Is this correct? If so, does it mean that the polymix-4 workload
effectively doesn't include news sites (like the CNN example in the object
life cycle documentation) in its workload model?
Small nit: the object life cycle documentation is out of sync with the
code at the moment. (It talks about the birthday field, which is no longer
used in polygraph 2.7.5.) The affected pages are
http://www.web-polygraph.org/docs/reference/models/objlife.html#modification
http://www.web-polygraph.org/docs/reference/pgl/types.html#type:docs/reference/pgl/types/distr
Thanks!
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