4.1. TIMELINE CHARTS
Figure 4.4: Search for MPI Bcast in the Master Timeline
Figure 4.5: Active overlay showing PAPI FP OPS in the Master Timeline
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CHAPTER 4. PERFORMANCE DATA VISUALIZATION
Symbol
Description
Message Burst
Due to a lack of pixels it is not possible to display a
large amount of messages in a very short time interval.
Therefore outgoing messages are summarized as so-called
message bursts. In this representation you cannot deter-
mine which processes receive these messages. Zooming
into this interval reveals the corresponding single messages.
Markers
multiple
single
To indicate particular points of interest during the run-
time of an application, like errors or warnings, markers can
be placed in a trace file. They are drawn as triangles which
are colored according to their types. To indicate that two
or more markers are located at the same pixel, a tricolored
triangle is drawn.
I/O Events
Vampir shows detailed information about I/O operations, if
they are included in the trace file. I/O events are depicted as
triangles at the beginning of an I/O interval. In order to see
the whole interval of a single I/O event its triangle has to be
selected. In that case a second triangle indicating the end of
the interval appears. Multiple I/O events are tricolored and
drawn as a triangle with a line to the end of the interval.
Table 4.1: Additional Information in the Master and Process Timeline
A search string can be written in this field and all corresponding function and func-
tion group occurrences are highlighted in yellow in the “Master Timeline”. An example
search for the function MPI Bcast is depicted in Figure 4.4.
Furthermore, the “Master Timeline” also features an overlay mode for performance
counter data, Figure 4.5. In order to activate the overlay mode use the context menu
“Options → Performance Data”. When the overlay mode is active a control window
appears at the top of “Master Timeline”. It allows to select the displayed counter data
(metric). The counter data is displayed in a color coded fashion like in the “Performance
Radar”, Section 4.1.3. The color scale can be freely customized by clicking on the
wrench icon. The control window also provides an opacity control slider. This slider
allows to adjust the opacity of the overlay and thus makes the underlying functions
easily visible without the need to disable the overlay mode.
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4.1. TIMELINE CHARTS
4.1.2 Counter Data Timeline
Counters are values collected over time to count certain events like floating point op-
erations or cache misses. Counter values can be used to store not just hardware
performance counters but arbitrary sample values. There can be counters for different
statistical information as well, for instance counting the number of function calls or a
value in an iterative approximation of the final result. Counters are defined during the
instrumentation of the application and can be individually assigned to processes.
Figure 4.6: Counter Data Timeline
An example “Counter Data Timeline” chart is shown in Figure 4.6. The chart is re-
stricted to one counter at a time. It shows the selected counter for one measuring point
(e.g., process). Using multiple instances of the “Counter Data Timeline”, counters or
processes can be compared easily.
The displayed graph in the chart is constructed from actual measurements (data points).
Since display space is limited it is likely that there are more data points than display
pixels available. In that case multiple data points need to be displayed on one pixel
(width). Therefore the counter values are displayed in three graphs. A maximum line
(red), an average line (yellow), and a minimum line (blue). When multiple data points
need to be displayed on one pixel width, the red line shows the data point with the
highest value, the blue line shows the point with the lowest value, and the yellow line
indicates the average of all data points lying on this pixel width. When zooming into an
smaller time range less data points need to be displayed on the available pixel space.
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CHAPTER 4. PERFORMANCE DATA VISUALIZATION
Eventually, when zooming far enough only one data point needs to be display on one
pixel. Then also the three graphs will merge together. The actual measured data points
can be displayed in the chart by enabling them via the context menu under “Options...”.
Figure 4.7: Select metric dialog
The context menu entry “Select Metric...” opens the selection dialog depicted in Fig-
ure 4.7. This dialog allows to choose the displayed counter in the chart. Each counter
is defined by its metric and its measuring point. Note, depending on the measurement
not all metrics might be available on all measurement points.
The two left buttons in the dialog decide whether the counter should be selected by
metric or by measuring point first. In the case of “Select by Metric” there is also the op-
tion to “Summarize multiple measuring points” available. This option allows to identify
outlier by summarizing counters (e.g., PAPI FP OPS) over multiple measuring points
(e.g., processes). Hence, when this option is active multiple measuring points can be
selected. The counter for the selected metric is then summarized over all selected
measuring points. The displayed counter graphs in the chart need then to be read
as follows. The yellow “average” line in the middle displays the average value (e.g.,
PAPI FP OPS) of all selected measuring points (e.g., processes) at a given time. The
red “maximum” line shows the highest value that one of the selected measuring points
achieved at a given time. The blue “minimum” line shows the smallest value that one
of the selected measuring points (e.g., process) achieved at a given time. A click with
the left mouse button on any point in the chart reveals its details in the “Context View”
display. Stated are the min, max, and average values and the measurement points
(e.g., processes) that achieved maximum and minimum values at the selected point in
time.
The options dialog is depicted in Figure 4.8. It can be enabled via the context menu
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