#9 Add % of process time to the output

open
nobody
None
5
2007-04-14
2007-04-14
Andrew Wilcox
No

Currently, JIP reports percent-times on a per-thread basis. If, for example, you have a process that has multiple threads, the total percent times will add up to more that 100%. So it would be nice to see timing reported relative to the total processes in addition to being reported as a percent per thread.

Discussion

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    Are we seeing CPU time or real time in the data?

     
  • Andrew Wilcox
    Andrew Wilcox
    2008-03-10

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    You are seeing CPU time rather than real time. If you have a multi-threaded program running on a machine with multiple cores, the total time as profiled could be greater than the time you would see using a stop watch. For example, a program with two threads where each thread runs for a second would be profiled as having used 2 seconds of CPU time. On a single processor box, the program would run for two seconds, but on a multicore box it would run in just one second (this is a simplified example that ignores JMV start-up time, classloading time and CPU cycles consumed by other processes).