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12c: Warning Message About Heavy Swapping Observation and ORA-700 [kskvmstatact: excessive swapping observed] (Doc ID 1919850.1)

Last updated on FEBRUARY 01, 2022

Applies to:

Oracle Database Exadata Express Cloud Service - Version N/A and later
Oracle Database Cloud Service - Version N/A and later
Oracle Database - Enterprise Edition - Version 12.1.0.1 to 12.2.0.1 [Release 12.1 to 12.2]
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Oracle SuperCluster M7 Hardware - Version All Versions to All Versions [Release All Releases]
Information in this document applies to any platform.

Symptoms

With 12cR1, if the sum of swap+in and swap+on is more that 2% of the real memory of the system, alert_<sid>.log reports frequent information about memory being swapped like below:

...
WARNING: Heavy swapping observed on system in last 5 mins.
pct of memory swapped in [2.70%] pct of memory swapped out [0.00%].
Please make sure there is no memory pressure and the SGA and PGA
are configured correctly. Look at DBRM trace file for more details.
Errors in file <ADR_BASE>/diag/<product_type>/<prod_id>/<instance_id>/trace/<SID>_dbrm_21092.trc  (incident=16909):
ORA-00700: soft internal error, arguments: [kskvmstatact: excessive swapping observed], [], [], [], [], [], [], [], [], [], [], []
Incident details in: <ADR_BASE>/diag/<product_type>/<prod_id>/<instance_id>/incident/incdir_16909/<SID>_dbrm_21092_i16909.trc
...


The sum of the pct memory swapped in and swapped out always appears to be higher that 2%.

The DBRM trace file shows information similar to:

Heavy swapping observed in last 5 mins:    [pct of total memory][bytes]
total swpin [ 3.60%][599496K], total swpout [ 0.00%][0K]
vm stats captured every 30 secs for last 5 mins:
swpin:                 swpout:  
[ 0.07%][     12416K]  [ 0.00%][         0K]
[ 0.38%][     63712K]  [ 0.00%][         0K]
[ 0.05%][      9432K]  [ 0.00%][         0K]
[ 0.81%][    135488K]  [ 0.00%][         0K]
[ 0.35%][     59032K]  [ 0.00%][         0K]
[ 0.22%][     37744K]  [ 0.00%][         0K]
[ 0.35%][     58544K]  [ 0.00%][         0K]
[ 0.62%][    104592K]  [ 0.00%][         0K]
[ 0.56%][     93368K]  [ 0.00%][         0K]
[ 0.15%][     25168K]  [ 0.00%][         0K]
Heavy swapping observed in last 5 mins:    [pct of total memory][bytes] 


In 12.2, you will have some additional information in the incident trace file which will help you determine if the is a problem. The information also contains recommendations on 
actions to avoid the error as seen below; 

==========================================
INSTANCE-WIDE SWAP ALERT SUMMARY
------------------------------------------
WARNING: Heavy swapping observed on the system.
Heavy swapping can lead to timeouts, poor performance, and instance eviction.
To reduce swapping, reduce the memory usage of this database instance and/or 
other applications running on this server.
 
total physical memory:                    64266 MB
bytes swapped in/out in last 5 mins:    1965460 KB
cpu utilization:                             40%
 
SGA_TARGET:                               24576 MB
 
PGA_AGGREGATE_LIMIT:                          0 MB
maximum PGA allocated since startup:      31282 MB
total PGA currently allocated:            31172 MB
PGA_AGGREGATE_TARGET:                      5120 MB
 
Beware that PGA usage (31282 MB) exceeds PGA_AGGREGATE_TARGET (5120 MB).
Decrease PGA usage by lowering PGA_AGGREGATE_TARGET and PGA_AGGREGATE_LIMIT.
 
Reduce the memory usage of this database instance by lowering SGA_TARGET, 
PGA_AGGREGATE_TARGET, and/or PGA_AGGREGATE_LIMIT.

 
and the call stack trace associated with this incident looks like:

----- Call Stack Trace -----
... kskvmstatact kskdbrmtoutact ksbcti ksbabs ksbrdp opirip opidrv sou2o ...

 

Changes

Upgraded to 12.1.

Cause

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In this Document
Symptoms
Changes
Cause
Solution
References


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