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

eee[%]
is the percentage of paging exposures the scheduler is to view when
considering adding a loading E2 or E3 user to the dispatch list. If the
number of Q2 and Q3 loading users currently in the dispatch list plus
the loading E2 or E3 user under consideration exceeds the eee
percentage of paging exposures, the user may not be added
immediately and is delayed further.
fff[%] is the percentage of paging exposures the scheduler should view when
considering adding a loading E3 user to the dispatch list. If the number
of Q3 loading users currently in the dispatch list plus the loading E3
user under consideration exceeds the fff percentage of paging
exposures, the user may not be added immediately and is delayed
further.
Note that in order to enter the dispatch list, an E1 user must only pass the one
barrier established by ddd. But an E2 user must pass the two barriers set by
ddd and eee. And an E3 user must pass the three barriers set by ddd, eee, and
fff. This is exactly analogous to the operation of STORBUF, though STORBUF
was explained differently. Similarly, the differences between the values (ddd-eee
and eee-fff) represent LDUBUF buffers (for Q1 and Q2 respectively), just as
they do for STORBUF.
In each case, the LDUBUF values must be in the range 0 through 999, with a
restriction that ddd ≥ eee ≥ fff. Any value greater than 100 represents an
overcommitment of DASD paging capacity.
LDUBuf INITial
sets the percentage parameters back to their initial values, 100%, 75%, and
60%.
DSPBuf {iiiii jjjjj kkkkk}
gives the scheduler criteria for admitting users to the dispatch list in cases of
users who are not prevented from entering by the more resource-specific
barriers established by STORBUF and LDUBUF. DSPBUF stands for “dispatch
buffer” and refers to the total number of users (by class) that are allowed in the
dispatch list.
The operand iiiii refers to the number of openings in the dispatch list made
available to users with short-running (E1) transactions. A subset, jjjjj, of the iiiii
openings is also made available to users with medium-length transactions; the
E1 and E2 users compete for these slots. Another subset, kkkkk, of the jjjjj
openings is also made available to users with long-running transactions; the E1,
E2, and E3 users all compete for these slots. QUICKDSP and other E0 users
are not limited by these numbers and may enter the dispatch list without limit.
The valid range of values is 1 to 32767 where iiiii ≥ jjjjj ≥ kkkkk
Example: dspbuf 35 30 18
SET SRM
35 openings are available to E1 users, but only 5 of them (5 = 35 − 30) are
exclusively available to E1 and are guaranteed not to be already occupied by
E2 and E3 users.
30 openings are available to E2 users, but only 12 of them (12 = 30 − 18) are
guaranteed not to be already occupied by E3 users. None of the 30 openings is
guaranteed against occupation by E1 users; however, E1 users generally get
out of the way quickly.
Chapter 2. CP Commands 1393