Abstract: Embodiments of the present invention provide for performance monitoring of virtualized environments by establishing external performance monitoring (in a primary domain) of a virtual machine manager in whose context a virtual machine operates, and simultaneously capturing information on the virtual machine execution states. In accordance with an embodiment of the present invention, the execution states may comprise any combination of a virtualized processor index, execution address, program (task) identifier, and a timestamp. In one embodiment, a primary domain performance monitoring component may initiate time- or event-based profiling of the virtual machine, and a hypervisor may report the virtualized execution states to the performance monitoring component upon reception of each profiling interrupt. Alternatively, the time-based profiling may be initiated in the virtual machine domain.

Abstract: Efficient performance monitoring for symmetric multi-threading systems is applicable to systems that have limited performance monitoring resources and enables efficient resource sharing on a per-execution unit basis. The performance monitoring unit being shared is programmed to reset its counter and to start performance monitoring operation if there is only one execution unit requesting this operation. In case there are several requests pending, an attempt is made to program the performance monitoring unit to collect performance data for a subset of execution units the hardware is capable to support. Upon a request to stop performance monitoring operation the previously allocated indicator may be removed, and the performance monitoring unit may be programmed to stop operating if there are no more active or pending requests. In case the performance monitoring was inactive for the current execution unit, this request may be discarded, and no performance data may be returned.

Abstract: Embodiments of the present invention provide for performance monitoring of virtualized environments by establishing external performance monitoring (in a primary domain) of a virtual machine manager in whose context a virtual machine operates, and simultaneously capturing information on the virtual machine execution states. In accordance with an embodiment of the present invention, the execution states may comprise any combination of a virtualized processor index, execution address, program (task) identifier, and a timestamp. In one embodiment, a primary domain performance monitoring component may initiate time- or event-based profiling of the virtual machine, and a hypervisor may report the virtualized execution states to the performance monitoring component upon reception of each profiling interrupt. Alternatively, the time-based profiling may be initiated in the virtual machine domain.

Abstract: The method disclosed may be used together with any prefix oriented decoding method to enable faster decoding of variable length codes when a subset of most frequently used codes with relatively short prefixes may be determined. An embodiment of the present invention reads a number of bits, not less than the maximal possible length of a code, from a bit stream. Then a predetermined number of bits is selected and used as an index to a data structure that contains at least a decoded value and a validity indicator, along with other pre-decoded data, namely: prefix type and length, maximal code length for a group of codes, actual code length, the number of bits to return to the bit stream, etc. The validity indicator is used to determine whether to proceed with the decoding operation, or obtain the valid decoded value from the data structure and return excess bits to the bit stream.