Warning: VKTM detected a time stall.
Time drifts can result in unexpected behavior such as time-outs.
Please see the VKTM trace file for more details:
# service ntpd status
ntpd is stopped
Trace file /u01/app/oracle/diag/rdbms/db/db/trace/db_vktm_63714.trc
Oracle Database 12c Enterprise Edition Release 188.8.131.52.0 - 64bit Production
Build label: RDBMS_184.108.40.206.0_LINUX.X64_170125
System name: Linux
Node name: db1
Version: #1 SMP Thu Jul 23 15:44:03 UTC 2015
Instance name: db12
Redo thread mounted by this instance: 0
Oracle process number: 6
Unix process pid: 63714, image: oracle@db12 (VKTM)
*** 2019-02-10T15:09:46.168294+08:00 (CDB$ROOT(1))
*** CLIENT ID:() 2019-02-10T15:09:46.168349+08:00
*** SERVICE NAME:() 2019-02-10T15:09:46.168357+08:00
*** MODULE NAME:() 2019-02-10T15:09:46.168363+08:00
*** ACTION NAME:() 2019-02-10T15:09:46.168372+08:00
*** CLIENT DRIVER:() 2019-02-10T15:09:46.168379+08:00
[kji_attach][LMON !running, !call kjual]
*** SESSION ID:(727.45771) 2019-02-10T15:09:46.172975+08:00
*** SERVICE NAME:() 2019-02-10T15:09:46.172994+08:00
*** CONTAINER ID:(1) 2019-02-10T15:09:46.173001+08:00
kstmmainvktm: succeeded in setting elevated priority
VKTM running at (1)millisec precision with DBRM quantum (100)ms
[Start] HighResTick = 75394510316
kstmrmtickcnt = 0 : ksudbrmseccnt = 1549782586
kstmchkdrift (kstmhighrestimecntkeeper:lowres): Time moved backward by (68)microsecs at 1550713032
*** 2019-02-21T09:36:10.411244+08:00 (CDB$ROOT(1))
kstmchkdrift (kstmhighrestimecntkeeper:lowres): Time moved backward by (62)microsecs at 1550713032
kstmchkdrift (kstmhighrestimecntkeeper:lowres): Time moved backward by (56)microsecs at 1550713032
In general VKTM process need to be scheduled in every 10ms, if due to above reasons this is not happening, occurs less than 1sec and 5 sec then it is permissible.
Eventually, this probably would cause the resource manager to take improper decisions and can lead to a hang in worst case.
If the time drifts occurs less than 1sec and 5 sec for forward and backward respectively, then it is permissible and OK.
alter system set event="10795 trace name context forever, level 2" scope=spfile;
alter system set "_disable_highres_ticks"=true scope=spfile;
_timer_precision = 500