Perform some analysis of time drift in Oracle VKTM trace files.

 See vt.sh for an example usage.

SYNOPSIS


     Parse the timestamps and time adjustments from the trace file created by Oracle Database process VKTM
     https://docs.oracle.com/cd/E18283_01/server.112/e17110/bgprocesses.htm
 
     This script currently considers only highres forward time drifts

     See this Oracle Support Note:
     Time Drift Detected. Please Check VKTM Trace File for More Details (Doc ID 1347586.1)

     Time drifts of 1 sec forward are acceptable.
     Time drifts of 5 sec backward are acceptable.

     Drifts outside of these parameters should be investigated


     See this Oracle Support Note for a patch to reduce VKTM messages in 11.2 ASM alert logs
     ASM Instance Is Reporting "Warning: VKTM detected a time drift" (Doc ID 1678120.1)

OPTIONS

     -h | --help 
       show options

     --man 
       show all documentation

     --csv-output 
       output CSV format - default is RPT

     --forward-drift-threshold 
       for the standard report, display an arrow next to values exceeding this threshold
            default is 1 (second)


VKTM Trace file Format

     *** 2016-12-17 17:46:58.856
     *** SESSION ID:(1.1) 2016-12-17 17:46:58.856
     *** CLIENT ID:() 2016-12-17 17:46:58.856
     *** SERVICE NAME:() 2016-12-17 17:46:58.856
     *** MODULE NAME:() 2016-12-17 17:46:58.856
     *** ACTION NAME:() 2016-12-17 17:46:58.856

     kstmmainvktm: succeeded in setting elevated priority
     highres_enabled

     *** 2016-12-17 17:46:58.866
     VKTM running at (1)millisec precision with DBRM quantum (100)ms
     [Start] HighResTick = 1482014818866063
     kstmrmtickcnt = 0 : ksudbrmseccnt[0] = 1482014818
     kstmchkdrift (kstmhighrestimecntkeeper:highres): Time jumped forward by (1542116)usec at (1482017000433105) whereas (1000000) is allowed
     kstmchkdrift (kstmhighrestimecntkeeper:highres): Time jumped forward by (1457497)usec at (1482025556154868) whereas (1000000) is allowed
     kstmchkdrift (kstmhighrestimecntkeeper:highres): Time jumped forward by (1741601)usec at (1482028279593226) whereas (1000000) is allowed
     kstmchkdrift (kstmhighrestimecntkeeper:highres): Time jumped forward by (1465148)usec at (1482030458886280) whereas (1000000) is allowed
     kstmchkdrift (kstmhighrestimecntkeeper:highres): Time jumped forward by (1198164)usec at (1482031301932289) whereas (1000000) is allowed

     *** 2016-12-17 22:21:42.949
     kstmchkdrift (kstmhighrestimecntkeeper:lowres): Time stalled at 1482031302
     kstmchkdrift (kstmhighrestimecntkeeper:lowres): Stall, backward drift ended at 1482031303 drift: 1

     *** 2016-12-17 22:22:03.505
     kstmchkdrift (kstmhighrestimecntkeeper:highres): Time jumped forward by (4939246)usec at (1482031323505006) whereas (1000000) is allowed
     kstmchkdrift (kstmhighrestimecntkeeper:highres): Time jumped forward by (2850778)usec at (1482037600018932) whereas (1000000) is allowed
     kstmchkdrift (kstmhighrestimecntkeeper:highres): Time jumped forward by (1853895)usec at (1482046620148715) whereas (1000000) is allowed
     kstmchkdrift (kstmhighrestimecntkeeper:highres): Time jumped forward by (1183737)usec at (1482048031506463) whereas (1000000) is allowed
     kstmchkdrift (kstmhighrestimecntkeeper:highres): Time jumped forward by (2284330)usec at (1482056954557624) whereas (1000000) is allowed
     kstmchkdrift (kstmhighrestimecntkeeper:highres): Time jumped forward by (1800835)usec at (1482058839861395) whereas (1000000) is allowed