Manage virtual processors

To manage virtual processors, you need to initialize VP classes, add and drop VPs, and monitor VPs.

Initialize a VP class

Check your HCL® Informix® Administrator's Guide and the HCL® Informix® Administrator's Reference for information about VP-class initialization.

Add and drop VPs

You can add or drop virtual processors in a user-defined VP class or in the CPU VP class while the database server is online. Use onmode -p to add a VP to a class or to drop a VP from a class.

The following command adds one virtual processor to the newvp class (which the code fragment in Define a yielding user-defined VP class defines): 
onmode -p +1 newvp

To remove a virtual processor, specify a negative value in the -p option. For more information about the onmode utility, see the HCL® Informix® Administrator's Reference.

Monitor virtual processors

You can use the following onstat -g commands to monitor VPs:
  • onstat -g glo to generate information about global multithreading such as CPU use of virtual processors and total number of sessions.
  • onstat -g rea to generate information about the number of threads in the ready queue of the VP class.
  • onstat -g sch to generate information about the number of semaphore operations, spins, and busy waits for each virtual processor.

A user-defined VP class appears in the onstat -g glo output as a new process. You can use the -g glo option to find the virtual process in which your module is loaded. The following list shows the last section of the output of this onstat command.

Figure 1. The onstat -g glo command output
Individual virtual processors:
 vp    pid       class       usercpu   syscpu    total     Thread    Eff
 1     23322     cpu         26.15     1.11      27.26     185.03    14%
 2     23326     adm         0.00      0.05      0.05      0.00       0%
 3     23327     lio         0.07      0.82      0.89      34.74      2%
 4     23352     pio         0.02      0.59      0.61      7.20       8%
 5     23353     aio         1.12      2.30      3.42      78.70      4%
 6     23354     newvp       0.00      0.02      0.02      0.00       0%

In The onstat -g glo command output, the onstat utility displays CPU usage for the CPU VP as the first line of output. It displays the processor and CPU usage for the user-defined VP newvp.

For more information about the onstat utility, see the HCL® Informix® Administrator's Reference.

In addition, you can select information from the sysvpprof SMI table about the virtual processors that are currently running. The sysvpprof SMI table exists only in the sysmaster database.