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Example 2 -- multiple_events

This example is a expansion of the previous example that adds some math operations and additional TimeTrac instrumentation to time those functions. The example covers the following basic functions:

  1. TimeTrac Output -- Single Thread, Multiple Events.

  2. TimeTrac Output -- Measuring Time Between Events.

  3. TimeTrac Output -- Measuring CPU Usage.

  4. Source code -- multiple_events

  5. Multiple Events Summary



TimeTrac Output - Single Thread, Multiple Events

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If we run this program it will create a file named multiple_events.trc. If we then run TimeTrac, do a "Sort/By Increasing Name," we will see a display similar to the following.

TimeTrac Screenshot
We now have a visual presentation of 5 different events within a single thread. From the TimeTrac display, it is easy to see the sequence of function calls relative to each other and approximately how long each one took.


TimeTrac Output -- Measuring Time Between Events

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If however, we want to see more detail, we can drag the time bars such that the left time bar (hold left mouse button and move the mouse) is near the beginning of the third hello event, and the second time bar is near the beginning of the 4th hello event (set the pointer at the edge of the event and right click the mouse). Now to expand the screen, click on the icon for the time bars. We can now read directly the length (adjust the time bars if necessary) of time from one event to another, in this case the sequence from one hello to the next hello.
TimeTrac Screenshot
In this case, the total time for this series of events took approximately 215 microseconds. In a similar manner, we can use the controls to further shrink or expand the screen and to easily measure the time between any 2 events.


TimeTrac Output -- Measuring CPU Usage

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To view the CPU usage for each event, zoom out all the way and then click on View/CPU Usage in the Menu Bar:
TimeTrac Screenshot
Now observe that on the right side of the TimeTrac display, we have the amount of CPU Usage for each of the events and can quickly determine where we might best spend our algorithm efforts to make the application run faster. For example, speeding up "vinput" would provide a real benefit (it is currently using 44% of a cpu) but speeding up "hello" (at 6.7% of a CPU) would not help us very much.


Source Code

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Module TimeTrac Functions
multiple_events.c All calls -- TimeTrac User Guide
ex_math.c No TimeTrac calls
ex_misc.c No TimeTrac calls
sky_ex_inc.h See time_trac.h


Multiple Events Summary

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This example shows additional TimeTrac outputs for a single thread.

  • 10 executions of the same code sequence.
  • Multiple events within that sequence.
  • How to expand the events on the screen.
  • How to collect time between any two events.
  • How to quickly observe the CPU Usage for each event.



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