On Mon, 4 Mar 2002, Ping Du wrote:
> When looking into results generated by report generator, I assume
> that there is certain kind of relationship between mean response
> time and hit ratio, which is:
>
> Mean Response Time = Hit Response Time x Hit Ratio + Miss Response
> Time x (1 - Hit Ratio)
>
> However this seems not true after real calculation using data in
> the report.
Your assumption is correct. Please keep in mind, however, that there
are many ways to compute hit ratio. If you are using the hit ratio
computed by ReportGen, that ratio is based on client-side measurements
and takes only basic objects into account. In other words, a "hit" or
"miss" classification is performed for certain kinds of transactions
(where client-side classification is possible), and not for all
transactions.
Thus, your formula should work if you use mean response time for the
"basic" object class on the left hand side. I believe that mean
response time for the "basic" objects is shown in one of the report
tables.
The next version of the reporting tool (the one we used at the last
cache-off) provides hit ratio calculation based on client- versus
server-side comparison, which is more accurate and can be used in your
formula directly. The "old" hit ratio is also provided. The new
reporting tool will be available in 2.8 release.
Alex.
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