Abstract: A computer implemented method, apparatus, and computer program code for profiling an application. Execution of an application is monitored. A set of metrics relating to execution of the application occurring during monitoring execution of the application are collected to form a set of observed metrics. An execution environment overhead occurring with respect to the set of observed events is identified to form an identified execution environment overhead. The set of observed metrics is adjusted using the identified execution environment overhead to form a set of calibrated metrics.

Abstract: A computer implemented method, apparatus, and computer program product for processing events. Events occurring during execution of an application are monitored to form monitored events. A plurality of sequences of method types and transition types from the monitored events are identified to form an identified plurality of sequences of method types and transitions types. Overhead compensation values are identified for the identified plurality of sequences of method types and transitions types to form identified overhead compensation values. Observed metrics for the monitored events are adjusted using the identified overhead compensation values.

Abstract: A computer implemented method, apparatus, and computer usable program code to collect information for a system or processor having a transition between an idle state and a non-idle state to form collected system or processor information. The collected system or processor information is provided for analysis by an application.

Abstract: A method, system, apparatus, and computer program product is presented for tracing operations. A set of related methodologies can be used within instruction tracing software, such as a tracing program, to reduce its tendency to generate interrupts that cause unwanted effects in the system that is being captured. A first methodology allows access to protected memory blocks so that instructions may be read from those memory blocks. A second methodology provides for the trace output buffer to be accessed using physical addressing. A third methodology traces only instruction addresses, which are resolved later during a post-processing phase of operation. A fourth methodology comprises multiple different methods for obtaining copies of instructions that have already executed rather than obtaining them before they are executed.

Abstract: A method and apparatus for identifying differences in runs of a computer program that are due to changes in the code of the computer program. With the apparatus and method, call trees are generated for two or more builds of a computer program. The apparatus and method perform a “tree-subtract” operation in which the two or more call trees generated during runs of two or more different builds of a computer program are subtracted from one another to identify build to build differences in the execution of the computer program. From the resulting tree, portions of the runs of the different builds of the computer program where the resource utilization of the computer program has not changed are easily identifiable. Moreover, portions of the runs of the different builds of the computer program where there are improvements or regressions in resource utilization of the computer program may be easily identifiable.

Abstract: A method, system, apparatus, and computer program product is presented for processing instructions. A processor is able to receive multiple types of interruptions while executing instructions, such as aborts, faults, interrupts, and traps. A set of processor fields are used to indicate whether or not one or more trap modes are active, such as a single-step trap mode or a taken-branch trap mode. The activity of a trap mode is conditioned, i.e., restricted, modified, or qualified, with a trap mode conditioning field that indicates whether or not the trap mode should remain active during interruption processing. The use of a trap mode conditioning field allows an interruption handler to run at full speed without being interrupted by the trap mode, yet the trap mode is preserved so that other processing, such as instruction tracing, may continue after interruption processing.

Abstract: An improved method, apparatus, and computer instructions for compressing trace data. An instruction stream is identified, and in response to identifying the instruction stream, the instruction addresses in the instruction stream are replaced with a stream identifier to form compressed trace data. Data addresses may be related to instructions in the instruction stream to generate a data trace component in the compressed trace data.

Abstract: A method and apparatus for automatically performing regression processing on trace data are provided. With the apparatus and method, call tree data structures are generated for two or more executions of two or more builds of a computer program. The apparatus and method perform a “tree-minimization” operation on each set of call tree data structures for each of the builds to generate minimized call tree data structures for each build of the computer program. The minimized call tree data structures are then subtracted from one another to generate a subtracted minimized call tree data structure. From this subtracted minimized call tree data structure, the portions of the computer program that are different from build to build and which appreciably and consistently affect the difference in execution of the computer program from build to build may be identified.

Abstract: A method, apparatus, and computer instructions in a data processing system for processing instructions are provided. Instructions are received at a processor in the data processing system. If a selected indicator is associated with the instruction, counting of each event associated with the execution of the instruction is enabled. In some embodiments, a compiler may obtain performance profile data, annotated by output obtained from the use of the performance indicators and counters, along with the instructions/data of the computer program and use this information to optimize the manner by which the computer program is executed, instructions/data are stored, and the like. The optimizations may be to optimize the instruction paths, optimize the time spent in initial application load, the manner by which the cache and memory is utilized, and the like.

Abstract: An improved method, apparatus, and computer instructions for generating trace data. In response to detecting a trace event, a determination is made as to whether identifiers for the trace event match recorded identifiers for a record in a set of previously recorded trace events. Location information for the record is placed in the trace data if a match between identifiers for the trace event and recorded identifiers for the record in the set of previously recorded trace events.

Abstract: A computer implemented method, apparatus, and computer usable program code for sampling call stack information. An event is monitored during execution of a plurality of threads executed by a plurality of processors. In response to an occurrence of the event, a thread is identified in the plurality of threads to form an identified thread. A plurality of sampling threads is woken, wherein a sampling thread within the plurality of sampling threads is associated with each processor in the plurality of processors and wherein one sampling thread in the plurality of sampling threads obtains call stack information for the identified thread.

Abstract: A method, apparatus, and computer instructions for presenting coverage data for code. The coverage data containing instruction access indicators associated with the code is obtained. Particular instruction access indicators that have been set by a processor in the data processing system in response to execution of the code by the processor are identified to form set instruction access indicators. Each set instruction access indicator is associated with a portion of the code. A presentation for the coverage data is generated. The set instruction access indicators are identified in the presentation. This presentation may be, for example, a graphical presentation.

Abstract: A computer implemented method, apparatus, and computer usable program code to collect information for a system or processor having a transition between an idle state and a non-idle state. Idle counts occurring during execution of code are collected to form collected system or processor information. The collected system or processor information is provided to an application for analyzing why a processor becomes idle.

Abstract: A method and system for tracing profiling information using per thread metric variables with reused kernel threads is disclosed. In one embodiment kernel thread level metrics are stored by the operating system kernel. A profiler request metric information for the operating system kernel in response to an event. After the kernel thread level metrics are read by the operating system for a profiler, their values are reset to zero by the operating system kernel. The profiler then applies the metric values to base metric values to appropriate Java threads that are stored in nodes in a tree structure base on the type of event and whether or not the kernel thread has been reused. In another embodiment non-zero values of thread level metrics are entered on a liked list. In response to a request from a profiler, the operating system kernel reads each kernel thread's entry in the linked list and zeros each entry.

Abstract: A method, apparatus, and computer instructions for presenting coverage data relating to data access occurring during execution of code. The coverage data containing data access indicators associated with memory locations is obtained. The data access indicators that have been set by a processor in the data processing system in response to access of the memory locations during execution of the code by the processor are identified to form set data access indicators. Each set instruction access indicator is associated with a portion of the memory locations allocated for the code. A presentation for coverage data is generated, wherein the set data access indicators are identified in the presentation.

Abstract: A system and method for Java™ call stack sampling combined with native sampling is presented. A kernel-mode device driver records and stores sampled context information that includes a program counter, a thread identifier, and a process identifier. The sampling thread receives a notification from the kernel-mode device driver, and proceeds to collect call stack information from a Java™ Virtual Machine. In turn, the sampling thread retrieves the sampled context information and harvests symbols corresponding to a loaded module. Once symbols are harvested, the sampling thread combines returned call stack nodes with native function leaf nodes into a unified output tree that provides the relationship between the two different node types. In one embodiment, the sampling thread may generate native function leaf nodes and the unified output tree in a post-processing manner.

Abstract: Method and apparatus for tracking thread stacks during a trace of a computer program. Hardware assistance mechanisms allow a processor to autonomically maintain a thread work area for each thread where a call stack is stored. An operating system informs the processor of the size of the data area to allocate to a particular thread work area. When a trace of a computer program is to be performed, trace software, informs the processor to begin maintaining thread call stack information in the thread work area. For each thread in the computer program execution, the processor maintains a work area having a size that is determined based on the size communicated by the operating system. The processor contains microcode to cause the processor to automatically store thread tracking information in the work areas designated by control registers of the processor when a control bit is set.

Abstract: A method and apparatus for automatically performing regression processing on trace data are provided. With the apparatus and method, call tree data structures are generated for two or more executions of two or more builds of a computer program. The apparatus and method perform a “tree-minimization” operation on each set of call tree data structures for each of the builds to generate minimized call tree data structures for each build of the computer program. The minimized call tree data structures are then subtracted from one another to generate a subtracted minimized call tree data structure. From this subtracted minimized call tree data structure, the portions of the computer program that are different from build to build and which appreciably and consistently affect the difference in execution of the computer program from build to build may be identified.

Abstract: A method and system for determining the memory utilization of a heap are provided. With the method and system, object allocations and optionally, possible memory freeing events are used to initiate a mark-and-count operation. The mark-and-count operation marks the live objects and maintains a running count of their memory bytes allocated to the live objects, referred to as a live count. The execution of the mark-and-count operation may be dependent upon various criteria including thresholds, functions of the live count, peak live counts, number of memory bytes allocated since a previous mark-and-count operation was performed, and the like. In addition to the live count, a total number of bytes allocated to objects may be maintained in order to obtain information regarding the heap memory utilization.

Abstract: A method, an apparatus, and a computer program product in a data processing system are presented for using hardware assistance for gathering performance information that significantly reduces the overhead in gathering such information. Performance indicators are associated with instructions or memory locations, and processing of the performance indicators enables counting of events associated with execution of those instructions or events associated with accesses to those memory locations. The performance information that has been dynamically gathered from the assisting hardware is available to the software application during runtime in order to autonomically affect the behavior of the software application, particularly to enhance its performance. For example, the counted events may be used to autonomically collecting statistical information about the ability of a software application to successfully acquire a semaphore.