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Performance Analysis Measurements
Model 1630A/D/G
5-4
State Label Overview Chart------------------------------------
Total samples 26152
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Program Activity Histogram of ROGP
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Figure 5-2. State Label Overview Chart of Example Measurement
Total Samples:
the total number of sampled states acquired and sorted at this point in time .
[Including] Field :
defines if percentages should be computed from the total samples or from the total
number of samples that fall within a defined range.
Histogram :
provides a percentage-based bar graph of range usage .
TIME INTERVAL OVERVIEW MEASUREMENT
Time Interval Overview Measurement provides a histogram of the time spent within a routine with a known
entry and known exit point, or the time spent between transition points . It is useful in finding exceptional cases
such as a routine that occasionally runs much too long, or much too short. It also provides information for code
optimization, allowing the programmer to optimize the code for the conditions under which a routine operates
the most .
For example, consider an interrupt driver that has only one entry point and one exit point. The interrupt driver
will call one of six predefined handlers, or will simply return, depending on the current system conditions and
register . Each of these handlers returns control to the driver, which returns control to the operating system
through its exit point.
The measurement is configured by setting the timer to start on the resource term [a], where [a] defines the
address of the entry to the routine, and by setting the timer to stop on the resource term [b], where [b] defines
the exit address of the routine. The time ranges are set to likely values by entering values and units for the limits
of each of the ranges from 1 to 8. Figure 5-3 is the State Line Interval Overview Trace Specification for this
example measurement .
As in State Label Overview, the analyzer runs in a continuous sample mode . A [start] trace is always
performed . When this example was run, the histogram in figure 5-4 was generated . The histogram indicates
that the majority of the time, the driver operates in the 1 .0 ms to 4 .0 ms range. It also shows that the driver
executes a great deal of the time in the 5.0 /us to 1 .0 ms range . Since the only handler to operate in the latter
range is the unknown interrupt case, the results indicate that there is a severe problem with undefined
interrupts . The maximum field indicates that one of the handlers can run for over 5 .0 ms . Since the handler
keeps interrupts turned off during this time, the large processor usage of this handler could be dangerous .
This measurement might also be used to monitor the time elapsed between the acknowledgement and
processing of an interrupt . In the case of a clock value update, large delays between the interrupt occurring
and the processing of the interrupt could indicate a slowing of the clock value .
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