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Tracing Hypervisor Activity Disclosure Number: IPCOM000013470D
Original Publication Date: 2003-Jun-18
Included in the Prior Art Database: 2003-Jun-18

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Operating system tracing, based on strategically located trace hooks throughout a kernel, including profile sampling trace hooks, are a primary means of OS performance tuning. The recent addition of logical partitioning (LPAR) introduced a new layer of code between the hardware and OS: the hypervisor. Unfortunately, when the machine is executing hypervisor code, ambiguities arise which make it impossible to distinguish hypervisor and real mode addresses in the trace/profile data. Profile samples within the hypervisor and during real mode (exception handling, etc) are not distinguishable and make it difficult to impossible to do performance analysis in either of these areas. As logical partitioning evolves and becomes more complex, it is increasingly important to be able to collect accurate profile information to allow performance analysis and tuning of the hypervisor s/w layer.