First Steps with PDA

Start PDA by running::

Configure a Project

PDA organizes data in projects and automatically starts with an empty project. You can add data to a project, save it with all its settings and later reload it.

Add Files to your Project

Click on Configure Project and select the file open symbol. Then select the file you would like to open, for example an iostat output file. PDA automatically tries to determine which parser might be capable of reading that file. This decision is mostly based on filenames, so don’t worry if PDA doesn’t auto-detect the parser. In the drop-down list, now select the parser to read this file and click ok.

Your file now appears in the Files section of the project. You may add as many files as you like. To delete the file again, click the trash icon, or click Settings to configure attributes of the parser.

Select the Series to display

Each parser provides the data in form of series, organized into categories and subcategories. Each series’s a name is a tuple of the form parser:category:subcategory:series. To select a series, click on the Select Series button and add a few series from the available series section. If there are no series available, the parser might not have been able to read your file. By typing in a pattern in the Filter field, you can filter for specific series (this fields supports regular expressions). Now click OK.

Depending on the parser, PDA typically reads your series data only after selecting a series, so this might take a few seconds.

In the Series section of the project you can now see all your selected series. PDA has automatically assigned a color to each of them. Behind their name, PDA displays the total number of samples and the automatically assigned value range (y-axis).

Configuring Series

Click on the Settings button of a series to change its name, its value range, or its color. Series data can be shown as curves using lines, but can also be displayed as impulses (vertical lines, which are usually used for event data) or dots or points for non-contiguous data. You may also change its line style and whether to use a linear or logarithmic y-axis. The Smooth field allows you to smooth the curve using an moving average, which is especially helpful if you have used a very short sampling interval and the curve is very unsteady.

The arrow up and down buttons behind the series allow you to move it up and down in the order.

Configuring Groups

Often you may want to group series. For example, mpstat gives you per-strand cpu data, but you may want to group all series from one core to get per-core data, or group them on a per-socket basis. In the same way, you could group aggregate activity from multiple disks, network interfaces, or any other source. To create and configure groups, click Configure Groups on the project dialog.

In the upper part of the window, you can create or delete groups, and in the lower part assign members to a group or remove them from a group. Members can be series from any parser. For each group, you can select an aggregation function to use to aggregate values from the members. For example, to aggregate context switches from mpstat on a per-core basis, you would usually select Sum to add them up, which for user cpu time, you would use Average to calculate their average across all strands.

Ideally the timestamps of your group members are all aligned. Per default PDA uses a tolerance of one seconds to aggregate samples from all members within the same second into a common sample.

Alter clicking OK, the group will be available as a special series with a parser name group. You can select your group by clicking Select Series and searching for series starting with group. Groups behave like any other series and can be configured in the very same way.

Setting a Title

The title you enter on the project dialog will appear in your graph as a title.

To display all selected series, close the project dialog by clicking OK.

Plotting Series in a Graph

The main window shows a graph of all your selected series. The top of the graph lists all series and their value ranges on the y-axis. [0; 100] means that values of this series will be scaled between 0 and 100 on the y-axis. Any series can use individual scales. Up to 4 y-axis are shown on the left an right. If you’re using more than 4 different scales, no further y-axis will be displayed, but data will still be scaled according to the range you have configured.

The x-axis shows time. Depending on your overall time range, days, hours, and or minutes are shown as units.

Zoom in and out

Just drag a rectangle with the mouse on any part of the graph, and PDA will zoom into that range. Please note that zooming just affects the x-axis, even though you have drawn a rectangle with the mouse. The y-axis is always kept constant.

To zoom out again, click the Reset Zoom button on the right.

Find your Series

See that one curve that has this severe drop? If you have added lots of curve, it might be tricky to figure out which curve that actually is, especially if you have many curves of similar or identical color. No worries! Just move your mouse over the series names on the right side of the window, and PDA will highlight each of the series for you. This way you can easily identify any series in the graph.

The small configure icon next to the series name directly takes you to the series configuration dialog.

Series Statistics

Now that you have displayed your data, you might want to get some statistics for the displayed series. Just click the Statistics button on the right to get statistics for all series, or any of the series buttons on the right to get individual statistics for a single series.

Statistics are always calculated for the zoom range you’re currently using. That means, if you zoom into a certain time period, only statistics for this period will be calculated.

PDA calculates mininum, average and maximum values for the samples of each series in that range, as well as variance and standard deviation. It also prints the number of samples found in that range, as well as the minimum, average, and maximum distance between any two samples in that interval.

Adding Labels

To annotate your data, you may want to add some labels to your graph. Just click Add Label on the right and enter a text. With the mouse, you can drag the label to any position in the graph. Clicking on the label again allows you to edit the text. By deleting the text, you can delete the label.

Labels use a fixed position and are not affected by zooming. Once you zoom in or out, the labels will remain on the screen where they are.

Printing and Saving the Graph

To print the graph, just click Print Image. To save it as a PNG image, click Save Image. Both printing and saving will use the resolution as shown on the screen. By maximizing your PDA window, you will create a larger image, and if you make your window small, your image will be smaller.

Saving and Loading Projects

If you’re done, you can save your project. This will save all settings of your project: your selected series, their properties, the groups you have created, the labels you put into the graph... To save a project, select Save or Save as from the Project menu. Note that your raw data files will not be saved as part of the project, and will be needed to open the project again.

To open a previously saved project, just select Open from the Project menu.