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CPU Constrained Database
The majority of wait time is spent performing computations. High
wait times can also be observed when the CPU run queue exceeds
the number of CPUs on the database server which can be isolated
by using the “r” column in vmstat UNIX. Having CPU time as a top
wait event is a plus for the DBA because the addition of faster
CPUs or more CPUs will relieve the bottleneck.
However, high CPU usage can also be indicative of excessive
Logical I/O (consistent gets) against the data buffers caused by
sub-optimal SQL. It can also be indicative of shared pool and
library cache contention. High CPU usage will be reported as a
top timed event.
Top 5 Timed Events
% Total
Event Waits Ela Time
---------------------------------- ------------ --------
CPU time 4,851 55.76
db file sequential read 1,968 27.55
log file sync 299,097 5.08
db file scattered read 53,031 4.55
log file parallel write 302,680 2.62
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