DB2 UDB for z/OS Version 8 Performance Topics - IBM Redbooks

► COPY varied from a 0% reduction, to a 10% increase in CPU
► REORG INDEX varied from a 10% to 17% reduction in CPU
► CHECK INDEX achieved a 3% increase in CPU
► RECOVER TABLESPACE also achieved a 3% increase in CPU
► UNLOAD achieved no increase CPU
► ONLINE REORG achieved a 4% increase in CPU
Refer to Chapter 6, “Utilities” on page 261 for a discussion of utility performance
enhancements in V8.
Overall, the utilities we studied achieved a -5% to +10% regression in CPU used in V8
compared with V7.
The RUNSTATS utility was by far the most variable. RUNSTATS TABLESPACE was generally
the best performer with its CPU to the left of the RUNSTATS bar. This was followed by
RUNSTATS TABLESPACE and TABLE, then RUNSTATS TABLESPACE and INDEX, with
RUNSTATS INDEX generally appearing to the right of the bar.
Important: The numbers we have presented in this section represent what we observed
from the laboratory measurements using a variety of different workloads. Your
performance studies most certainly vary. DB2 performance is very application and
workload dependent. Also remember that DB2 performance may vary every time
maintenance is applied to DB2.
Let us have a closer look at the IRWW workload, running in DB2 V7, DB2 V8 in CM and DB2
V8 running in NFM. Table 4-1 summarizes these results.
Table 4-1 CM vs. NFM - Non-data sharing
DB2 V7 DB2 V8
CM
Page-fixed Buffer Pools No Yes Yes
ETR
(commits / sec)
CPU
(%)
ITR
(commits / sec)
DB2 class 2 time
(msec / commit)
DB2 V8
NFM
Delta
(CM / V7)
Delta
(NFM / CM)
386.00 386.50 385.50 + < 1‘% + < 1%
63.79 64.41 64.11 + 1% - < 1%
605.11 600.06 601.31 - 1% + < 1%
Elapsed 15.148 15.922 15.462 + 5% - < 3%
CPU 1.713 1.842 1.815 + 7% - < 2%
DB2 class 2 CPU time
(msec / commit)
MSTR 0.096 0.107 0.107 + 11% 0%
Chapter 4. DB2 subsystem performance 133