Follow the procedure to set simulation parameters.
About this task
When you have opened a trace data file, as described in Selecting and opening a trace data file, and have clicked the Simulation
Parameters tab, the following page is displayed: Figure 1. Simulation – The Simulation Parameters window
This page shows a list of available buffer pools and
their default parameters, and it provides controls to select buffer
pools and change their parameters for the simulation.
The top of the page shows the full path and name of the trace
data file that you just opened.
Each row of the list represents a single buffer pool and its simulation
parameters. The list shows a set of 80 selectable buffer pools in
the ranges of BP0 to BP49 (the 4 KB buffer pools), BP8K0 to BP8K9
(the 8 KB buffer pools), BP16K0 to BP16K9 (the 16 KB buffer pools),
and BP32K0 to BP32K9 (the 32 KB buffer pools). Initially, active buffer
pools (those for which activities were recorded during the time trace
data was collected and stored in the trace data file) are preselected
in the Simulate column.
The Virtual sequential threshold field
shows the percentage of the virtual buffer pool that might be occupied
by sequentially accessed pages. The default value is 80%.
The Minimum buffer simulation size field
shows the minimum buffer pool size to be simulated. The size is shown
in number of buffer pool pages (whereby a single page has a size of
4 KB, 8 KB, 16 KB, or 32 KB, depending on the buffer pool).
The Maximum buffer simulation size field
shows the maximum buffer pool size to be simulated. The size is shown
in number of buffer pool pages.
The Interval field shows the increment
by which a buffer pool size is changed (between the minimum and maximum
size) during the simulation. The increment is shown in number of buffer
pool pages.
You use this page to determine which buffer pools you
want to include in the simulation and to specify individual simulation
parameters for each selected buffer pool.
Select one or more buffer pools
by selecting or clearing the respective checkboxes. You can also
use the Select all or Deselect all button
to act on active buffer pools. Select the Show only active
buffer pools checkbox to show only objects with buffer
pool activity.
You can adjust the initial simulation parameters as
required. Note that the time to perform a simulation increases with
the number of buffer pools and the different buffer pool sizes to
be simulated. Select the Simulate single combined buffer
pool checkbox to run the simulation for the preselected
buffer pools as a single combined buffer pool.
Example: With
the initial values shown on this page, Buffer Pool Analyzer will simulate
buffer pool sizes of 1 000, 2 000, 3 000 pages, and
so on, up to 20 000 pages, for a selected buffer pool.
For
practical reasons, choose a minimum and maximum buffer pool size and
an interval that does not result in more than 40 buffer pool sizes
per selected buffer pool. Otherwise, the time to generate the simulation
result increases excessively. In addition, the simulation result becomes
complex and difficult to interpret.
Note that you can sort the list by clicking a column header of
choice one or more times. Small arrows indicate the sort order.
Procedure
Review your selections and the simulation parameters for each selected buffer pool. To
modify a parameter, ensure that the buffer pool is selected. Then click the respective field
and edit the shown value. (Internally, the minimum, maximum, and interval values are slightly
rounded to avoid odd-numbered simulation cycles.)
