1 2 Previous Next 18 Replies Latest reply: Jun 28, 2009 7:42 PM by 655554 Go to original post RSS
      • 15. Re: how to troubleshooting high sys cpu usage ???
        546494
        hi,
        can you also provide vmstat and sar firgures.

        e.g. vmstat 5 13

        and sar for the whole day

        regards

        Alan
        • 16. Re: how to troubleshooting high sys cpu usage ???
          Jonathan Lewis
          jinyu wrote:
          Hi,I have post the top 5 event above.

          before tuning:
          Buffer Gets      Executions      Gets per Exec      %Total     CPU Time (s)     Elapsed Time (s)
          81,498     27,159     3.00     1.87     3.12     3.98     1prkhshjp25sc
          55,416     15,835     3.50     1.27     2.12     2.39     8tk22zsappg9m
          
          after tuning:
          
          Buffer Gets      Executions      Gets per Exec      %Total     CPU Time (s)     Elapsed Time (s)
          996,920     332,437     3.00     12.89     41.57     44.03     1prkhshjp25sc
          964,093     199,469     4.83     12.46     32.19     33.28     8tk22zsappg9m
          Looking at these figures it's not really surprising that you've seen no improvement in CPU usage - it looks as if any CPU you regain by tuning some expensive code is simply absorbed by an increase in the execution rate of statement like these two.

          Your "before" had about 110 sessions over three minutes, your "after had about 110 sessions over about 12 minutes - a factor of 4.3 increase. Your execution count for these two statements has gone up by a factor of about 13.

          What are these statements - are they some sort of polling statement in a tight loop that executes as fast as it can if there's CPU around ? Think about the numbers - 332,000 executions by 110 sessions in 13 minutes is an average of about 4 executions per session per second - that sounds suspiciously like a design flaw.

          Regards
          Jonathan Lewis
          http://jonathanlewis.wordpress.com
          http://www.jlcomp.demon.co.uk

          "For every expert there is an equal and opposite expert."
          Arthur C. Clarke
          • 17. Re: how to troubleshooting high sys cpu usage ???
            546494
            hi
            ,
            if you look at 'top' what are your load averages?

            to me it sound like you haqve insufficient cpus for your system. 40 runnable procs is very bad buy more cpus

            regards

            Alan
            • 18. Re: how to troubleshooting high sys cpu usage ???
              655554
              Thanks for your reply, the awr is just from stress testing,after tuning ,the system can support more user calls and executions , from the loadrunner's report ,response time per transaction decrease from 13s to 9s
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