Troubleshooting
Problem
While testing an OLTP workload, it was found that when migrating from DB2 V9.1 FP8 to DB2 V9.7 FP1, there was a significant performance regression observed in its runtime. This regression applies to subsequent DB2 9.7 fixpacks as well. The tests were executed on an AMD Opteron machine running Linux RHEL 5.4. When analyzing the profile of the workload via oprofile, we notice a 5x increase in the amount of CPU samples accounted to the kernel /boot/vmlinux*, particularly on do_gettimeoffset_pm().
Symptom
Slower OLTP workload performance running on Linux RHEL on AMD, when HPET (high precision event timer) is disabled in the operating system
[{"Product":{"code":"SSEPGG","label":"Db2 for Linux, UNIX and Windows"},"Business Unit":{"code":"BU058","label":"IBM Infrastructure w\/TPS"},"Component":"Performance - General\/Tuning","Platform":[{"code":"PF016","label":"Linux"}],"Version":"9.7","Edition":"Enterprise Server","Line of Business":{"code":"LOB10","label":"Data and AI"}}]
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Document Information
Modified date:
30 April 2025
UID
swg21443045