FCX237, I/O Priority Queueing Screen – IOPQUEUE

Performance Toolkit Subcommand: IOPQUEUE.

The I/O Priority Queueing Screen (FCX237) shows information on the use of the I/O priority queueing facility. User lines are shown highlighted on the screen if some of the I/Os got out-prioritized during the selected interval.

Figure 1. Layout of I/O Priority Queueing Screen (FCX237)

 FCX237      CPU nnnn  SER nnnnn  Interval HH:MM:SS - HH:MM:SS    Perf. Monitor

 I/O Priority Queueing HW active
 System minimum   9, maximum  15

 ______                       .        .      .        .         .
            Store  Range  <-Req. Range->  <-Eff. Range->  Outprior
 Userid     Subch   Type  R_Low   R_High  E_Low   E_High    Rate/s
 ACKERK        No    Abs      2       12      5       10       .00
 CFT2NDA      Yes    Rel      0        0      5        5       .00
 IRD00001      No    Rel     10       12      5        5       .00
 IRD00002      No    Rel      8       10      5        5       .00
 IRD00003      No    Rel     10       12      5        5       .00
 IRD00004      No    Rel     10       12      5        5       .00
 IRD00005      No    Rel     10       12      5        5       .00
 IRD00006      No    Rel     10       12      5        5       .00
 IRD00007      No    Rel      9       11      5        5       .00
 IRD00008      No    Rel     10       12      5        5       .00
 IRD00009      No    Rel     10       12      5        5       .00
 IRD00010      No    Rel     10       12      5        5       .00
 IRD00011      No    Rel     10       12      5        5       .00
 Select a user for user details
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The information shown is based on USER domain SAMPLE data. It is available only for z/VM 4.3 and later.

The sample shows a screen with the users sorted in ascending sequence of the user identifications, the initial setting (indicated by the underscore characters above the Userid header). Other possible sort sequences are indicated by dots above the corresponding columns. They can be set using the 'SORT' subcommand with the appropriate column heading as sort argument (see SORT), or by positioning the cursor on the header of the field which is to be sorted and then pressing ENTER.

For more detailed information on one specific user either:

Place the cursor on the Userid field of the virtual machine you are interested in and press ENTER, or
Enter the subcommand 'USER userid' on the command line

Field Description:

The main header shows whether the I/O priority queueing hardware facility is active or not. Note that CP will simulate the facility to allow prioritizing I/O requests from different virtual machines even when the corresponding hardware facility is not active. System minimum min, maximum max indicates the minimum and maximum range limits set for the system.

The remaining lines describe the I/O priority queueing settings and activity for individual virtual machines:

Userid

User identification of the virtual machine for which the line contains I/O priority queueing information.

Store Subch

Awareness of subchannel details by virtual machine.

Yes: Guest requested subchannel details which includes I/O priority facility status. This usually indicates that the guest is I/O priority aware, and that it may set its own I/O priorities.
No: Guest not aware of I/O priority facility. This indicates that changes to the priority of the virtual machine's I/Os can only be made by CP command.

Range Type

The range type set: can be either

Abs: If the range is absolute, or
Rel: If the range is relative.

Req. Range R_Low

The low value of the requested range.

Req. Range R_High

The high value of the requested range.

Eff. Range E_Low

The low value of the effective range.

Eff. Range E_High

The high value of the effective range.

Outprior Rate/s

The number of I/O requests that were outprioritized per second for this user. Note that this value refers to CP's simulation of the I/O priority queueing facility when passing on I/O requests from virtual machines to the hardware. It does not reflect the activity of the hardware feature.

Effect of AVERAGE and INTERIM subcommands:

Overall or interim period averages will be shown for all numerical fields.