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5. Interpreting Results

5.1 What are xact.level.mean, wait.level.mean, err xact.count?

The "level" represent the average number of established connections during the specified time interval (not connections established per second, that would be "rate"). In other words, if a "level" shows X established connections, it means that there were, on average, X established connections at any given time during the specified time interval.

"Xact" stands for active transactions, and "wait" stands for queued transactions waiting for connections to become available (due to open_conn_lmt).

In Polygraph terminology, "events per second" is called "rate" and "volume per second" is called "bandwidth". ".count" just means count, i.e., the total number of events observed. Thus, "err_xact.count" means the total number of erroneous transactions observed during the reported time interval.

5.2 Why is PolyMix-3 offered hit ratio not 55%?

Polygraph 2.5.1 has a minor bug in calculating offered hit ratio statistics. It will be fixed in the next release.

The problem is that Polygraph does not really know what is an offered hit and has to use heuristics to estimate the offered hit ratio using known request properties. Released Polygraph code does not account for Reload requests and thinks that a repeated request for a cachable object is always a hit. We need to exclude reloads from that rule. This is a statistics bug that has no effect on the actual request stream.

For now, you can assume that offered hit ratio is 55% (as it should be) and ignore related red flags.

5.3 gnuplot: Cannot open load file '-persist'

I tried to create reports after I created log files from both "polysrv" and "polyclt". I was able to run "label_results" without any problem both "polysrv" and "polyclt". However, I couldn't run "make_report" from "polyclt".

make_report: creating: `/tmp/polyrep/client-2.log/index.html'
./plot_traces: plotting: `/tmp/polyrep/client-2.log/rates.png'
         Cannot open load file '-persist'
         line 0: (No such file or directory)

Yes, this problem was reported to us once before. It looks like some installations of gnuplot do not understand "-persist" option regardless of the fact that the same installations document that option as being available.

The workaround is simple: comment out the "plotter_opts" line in the "reportgen.cfg" configuration file. If it does not help, please send details to bugs@web-polygraph.org.


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