High Resmgr:Cpu Quantum Wait Events In Standard Edition Oracle Database on Amazon Web Services
(Doc ID 2381153.1)
Last updated on JUNE 21, 2021
Applies to:
Oracle Database - Standard Edition - Version 11.2.0.4 and laterOracle Database Cloud Service - Version N/A and later
Oracle Database Cloud Schema Service - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Oracle Database Backup Service - Version N/A and later
Information in this document applies to any platform.
Symptoms
- High "resmgr:cpu quantum" Wait Events was observed In Standard Edition Oracle Database on Amazon Web Services server.
Statspack reports:
Top 5 Timed Events Avg %Total
~~~~~~~~~~~~~~~~~~ wait Call
Event Waits Time (s) (ms) Time
----------------------------------------- ------------ ----------- ------ ------
resmgr:cpu quantum 268,460 17,441 65 79.3
CPU time 3,494 15.9
log file parallel write 17,226 163 9 .7
log file sequential read 12,823 154 12 .7
db file sequential read 50,938 146 3 .7
-------------------------------------------------------------
- The number of CPUs reported by OS is only 2, and NICE_TIME (busy executing low-priority user code) is very high:
SQL> SELECT * FROM V$OSSTAT;
STAT_NAME VALUE
------------------------------ -----------
NUM_CPUS 2 *<<<<----
IDLE_TIME 708965289
BUSY_TIME 44222808
USER_TIME 7171195
SYS_TIME 4418388
IOWAIT_TIME 5521679
NICE_TIME 31636979 *<<<<----
RSRC_MGR_CPU_WAIT_TIME 13252256
STAT_NAME VALUE
------------------------------ -----------
NUM_CPUS 2 *<<<<----
IDLE_TIME 708965289
BUSY_TIME 44222808
USER_TIME 7171195
SYS_TIME 4418388
IOWAIT_TIME 5521679
NICE_TIME 31636979 *<<<<----
RSRC_MGR_CPU_WAIT_TIME 13252256
- From DBRM trace file, CPU wait time is much more than CPU time, and the total foreground process count both CPU running and CPU waiting is more than 16 often.
For example, as following, average foreground process running count is 2.30, and average average foreground process waiting for CPU is 21.30:
*** 2018-03-26 12:12:05.095
cpu%: cputm: cpuwt: avgrun: avgwt:
98 149577 1198969 2.30 21.30
cpu%: cputm: cpuwt: avgrun: avgwt:
98 149577 1198969 2.30 21.30
Changes
Cause
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In this Document
| Symptoms |
| Changes |
| Cause |
| Solution |