Graphics

Enter the command graphics to activate the graphics selection menu. It allows you to specify what kind of graphics should be shown: source of data, period to be selected, and the variables which are to be displayed.

For example:
  • The Format field shows GDDM initially, meaning that GDDM graphics would be generated. let us assume that GDDM is not installed on your system, and that you want to create a simple plot instead. There are two methods, and you just learned about the first one, context help.
    • Move the cursor to the Format line and press F1. You should see a help window which explains that the string PLOT must be inserted.
    • Press F12 to return.
    Knowing now that we should replace the string GDDM by the string PLOT you could just key in the new specification, but let us try another way first. The text below the selection fields tells you that instead of directly keying in your selection you can also enter a question mark (or any other invalid selection, actually) to be prompted with a more detailed selection menu:
    • Enter a question mark ? at the beginning of the input field for the Format selection and press ENTER. A window with a list of the valid selections and their explanation should be shown.
    • Move the cursor in front of the PLOT selection and press ENTER.
    Note that the field on the GRAPHICS selection menu has changed and that it now contains the string PLOT.
  • Press ENTER to build graphics based on the current selection. You should see a plot for '% total CPU' the total CPU load, and 'Cl1 85% time' the length of the (major) class 1 dispatch time slice.

    Press F12 to return to the selection menu.

  • Let us see how the output looks if a single variable has been selected: Overtype the string C1ES which describes the second Y-variable with blanks (at least one blank required, an 'erase field' is not sufficient) and press ENTER. You should see a plot for the total CPU load only, where the CPU load is shown in the form of a bar chart, not just as single markers. This format is always used when displaying a single variable.

    Press F12 to return to the selection menu.

  • Let us try to select a new second performance variable. Move the cursor to the field for the second Y-variable which is blank at the moment, key in a question mark ? and press ENTER.

    You will see a variable selection menu with a list of all the performance variables whose values can be plotted.

  • Move the cursor down to the field IO/S and press ENTER.

    Note that the second Y-variable is now set to IO/S i.e. it will show the system's real I/O activity.

  • Press ENTER again. A plot for total CPU time (we have not touched the definitions for the 1st variable) and the 'SSCH rate/s' should be shown.

    Press F12 to return to the graphics menu.

  • If GDDM is available on your system overtype the current format definition of PLOT with GDDM and press ENTER. You should now have GDDM graphics for the same data which you just plotted in the previous paragraph.

    Press F12 to return to the graphics menu.

  • All the graphical displays we've seen so far were 'by time' graphics, i.e. the X-axis was used as a time scale, as specified by the 'DETailed history' definition in the Graphics type input field. Enter a question mark ? on the Graphics type input field and press ENTER.

    You will see a selection menu which offers DETailed history, SUMmary history and VARiable correlation as possible choices. (Note that the selection PROfile history is not highlighted, i.e. is not valid at the moment. It can be specified only when a condensed history file of filetype PERFHIST is used as input.)

  • Move the cursor to the VARiable correlation selection and press ENTER. The graphics type field should now have changed to VARiable correlation and the field describing the X-variable should have been set for the default X-variable 'ACT' (number of active users in a sample interval).
  • Press ENTER. You should see a variable correlation plot where the same Y-variables we had used before are now plotted as a function of the number of active users. This kind of plot can be very useful on systems with a large number of CMS users, where it can show probable trends in resource utilization which allow extrapolation for different numbers of active users.

    Press F12 to return to the graphics menu.

See the Graphical Displays of Performance History Data section in the z/VM: Performance Toolkit Reference for a detailed description of all the different kinds of graphics which can be generated.

Enter the command basic. This should bring you back to basic mode.

This is the end of our short tour through the performance monitoring part of Performance Toolkit. See Operation in Performance Monitor Mode for a more detailed introduction to performance monitoring.