2843506 - 100% CPU usage on Time Stamp Counter (TSC)

• The HANA System's CPU utilization is exhausted on at least one host or more.
• Even after a full restart of the DB , another massive CPU load and/or blocked transactions are observed on the system.
• From the kernel profiler trace  (1804811 - SAP HANA Database: Kernel Profiler Trace), one particular callstack module is observed:

        The main single CPU consumer is: vgettimeofday

      Node Legend:
      <funcName>
      I: <function and descendant CPU time>
      E: function only time
     (Sys: I: <function and descendant time>, E: function only time)

   So in this example, the CPU is consumed by 22% alone for timestamp calls. This is not normal behavior.

   The indexserver trace also shows us that we have a system timer fallback:

   2019-08-19 13:28:24.081575 w Basis Timer.cpp(00718) : Fallback to system call for HR timer

• A high frequency of SQLExecutor threads with this callstack is observed in the indexserver runtime dumps :

       [thr=99546]: SqlExecutor at

       1: 0xffffffffff60017b in [vgettimeofday]+0x177 (<unknown>)

• A check of the clocksource from OS layer on the Linux host reveals it is not set at 'tsc'

  ~]# cat /sys/devices/system/clocksource/clocksource0/current_clocksource

Image/data in this KBA is from SAP internal systems, sample data, or demo systems. Any resemblance to real data is purely coincidental.

• SAP HANA Database Platform Edition 1.0 
• SAP HANA Database Platform Edition 2.0
• Intel CPUs 

vgettimeofday, High CPU, tsc, clocksource , KBA , HAN-DB-PERF , SAP HANA Database Performance , Problem