z/VM: CP Commands and Utilities Reference - z/VM - IBM

third time slice the user receives only a small boost in the dispatch list. On the
fourth and subsequent time slices the user receives no interactive boost at all.
If mmm is specified without nnn, the current interactive bias duration is not
changed.
IABias INITial
sets the intensity (mmm) and duration (nnn) back to the initial values, 90 and 2.
DSPSlice minslice
is the new size, in milliseconds, of the dispatching minor time slice. This is the
amount of CPU time a virtual machine may consume before reexamination by
the scheduler. The value minslice must be in the range of 1 to 100.
STORBuf {aaa[%] bbb[%] ccc[%]}
partitions the scheduler’s view of main storage when it chooses users to move
from the eligible list to the dispatch list. The result is a buffering mechanism
based on the transaction class of a user:
E1, Q1
— users with short-running transactions
E2, Q2
— users with medium-running transactions
E3, Q3
— users with long-running transactions,
En is the class assigned to a user in the eligible list, and Qn is the designation
after moving to the dispatch list. An E1 user in the eligible list becomes a Q1
user in the dispatch list, for example. Also, there is transaction class Q0, which
is users who never wait in the eligible list to contend for resources in the
dispatch list (for example, users with the QUICKDSP attribute).
The STORBUF values partition pageable storage. They are (in reverse order,
for clarity):
ccc[%]
is the maximum percentage of storage that dispatch list Q3 users can
occupy with their working sets.
bbb[%]
is the maximum percentage of storage that Q2+Q3 users together can
occupy. The percentage of storage represented by the difference
bbb-ccc represents a buffer of storage available to Q2 users that the
Q3 users are not allowed to use. This buffer protects the Q2 users from
delays that occur when slow-moving Q3 users take more (or all) of
storage.
aaa[%]
SET SRM
is the maximum percentage of storage that Q1+Q2+Q3 users can
occupy. The percentage of storage resulting from the difference
aaa−bbb represents a buffer of storage available to Q1 users that the
Q2 and Q3 users are not allowed to use. Without this buffer Q2 and Q3
users might occupy all of storage, causing long delays to E1 users who
could not enter the dispatch list until one of the slow-moving Q2 or Q3
users left. With the buffer, E1 users enter the dispatch list fairly quickly.
Since the buffer is never occupied by Q2 or Q3 users, an E1 user can
either enter the dispatch list immediately (if the buffer is not filled), or at
worst have only to wait for some Q1 user (in the buffer) to leave.
Chapter 2. CP Commands 1391