Abstract: A processor system tracks, in at least one counter, a number of cycles in which at least one execution unit of at least one processor core is idle and at least one thread of the at least one processor core is waiting on at least one off-core memory access during run-time of the at least one processor core during an interval comprising multiple cycles. The processor system evaluates an expected performance impact of a frequency change within the at least one processor core based on the current run-time conditions for executing at least one operation tracked in the at least one counter during the interval.

Abstract: A computing device identifies a load instruction and store instruction pair that causes a load-hit-store conflict. A processor tags a first load instruction that instructs the processor to load a first data set from memory. The processor stores an address at which the first load instruction is located in memory in a special purpose register. The processor determines where the first load instruction has a load-hit-store conflict with a first store instruction. If the processor determines the first load instruction has a load-hit store conflict with the first store instruction, the processor stores an address at which the first data set is located in memory in a second special purpose register, tags the first data set being stored by the first store instruction, stores an address at which the first store instruction is located in memory in a third special purpose register and increases a conflict counter.

Abstract: A computing device identifies a load instruction and store instruction pair that causes a load-hit-store conflict. A processor tags a first load instruction that instructs the processor to load a first data set from memory. The processor stores an address at which the first load instruction is located in memory in a special purpose register. The processor determines where the first load instruction has a load-hit-store conflict with a first store instruction. If the processor determines the first load instruction has a load-hit store conflict with the first store instruction, the processor stores an address at which the first data set is located in memory in a second special purpose register, tags the first data set being stored by the first store instruction, stores an address at which the first store instruction is located in memory in a third special purpose register and increases a conflict counter.

Abstract: A method of data processing includes a processor of a data processing system executing a controlling thread of a program and detecting occurrence of a particular asynchronous event during execution of the controlling thread of the program. In response to occurrence of the particular asynchronous event during execution of the controlling thread of the program, the processor initiates execution of an assist thread of the program such that the processor simultaneously executes the assist thread and controlling thread of the program.

Abstract: A performance projection system includes a test IHS and a currently existing IHS. The performance projection system includes surrogate programs and user application software. The test IHS employs a memory that includes a virtual future IHS, currently existing IHS, surrogate programs, and user application software for determination of runtime and HW counter performance data. The user application software and surrogate programs execute on the currently existing MS to provide designers with runtime data and HW counter or microarchitecture dependent data. Designers execute surrogate programs on the future IHS to provide runtime and HW counter data. Designers normalize and weight the runtime and HW counter data to provide a representative surrogate program for comparison to user application software performance on the future IHS. Using a scaling factor, designers may generate a projection of runtime performance for the user application software executing on the future IHS.

Abstract: A dual outcome event monitoring unit comprises a plurality of inputs, and a first counter. Each input is associated with an event and the first counter is a bidirectional counter. The dual outcome event monitoring unit is configured to increment the first counter in response to receiving an indication of the occurrence of a first event of a plurality of events. The first event is designated as an increment event. The dual outcome event monitoring unit is also configured to decrement the first counter responsive to receiving an indication of the occurrence of a second event of a plurality of events. The second event is designated as a decrement event.

Abstract: An indication that an event occurred is received from a processor by a dual outcome event monitoring unit. It is determined whether the event is associated with an increment event or a decrement event. In response to determining that the event is associated with the increment event, an event counter is incremented. The event counter is part of the dual outcome monitoring unit. In response to determining that the event is associated with the decrement event, the event counter is decremented.

Abstract: A processor of an information handling system (IHS) initiates an L3 cache prefetch operation in response to a demand load during instruction processing. The processor selects an L3 cache prefetch at random for tracking as a target prefetched instruction. The processor initiates an L1 cache target prefetch operation and stores the resultant target prefetched instruction in the L1 cache. If a demand load arrives, the processor analyzes the target prefetched instruction for effectiveness and determines the source of the prefetch data. If a demand does not arrive, the processor tests to determine if the particular prefetched instruction timed out in the cache and identifies the ineffectiveness of the prefetch operation. The processor samples multiple prefetch operations at random and generates a history of prefetch effectiveness and other useful prefetch information. The processor stores the prefetch effectiveness information to enable reduction or removal of ineffective prefetch operations.

Abstract: According to one aspect of the present disclosure a method and technique for managing memory access is disclosed. The method includes setting a memory databus utilization threshold for each of a plurality of processors of a data processing system to maintain memory databus utilization of the data processing system at or below a system threshold. The method also includes monitoring memory databus utilization for the plurality of processors and, in response to determining that memory databus utilization for at least one of the processors is below its threshold, reallocating at least a portion of unused databus utilization from the at least one processor to at least one of the other processors.

Abstract: In-memory accumulation of hardware counts in a computer system is carried out by continuously sending count values from full-speed hardware counter units to a memory controller. A sending unit periodically samples performance data from the hardware counter units, and transmits count values to a bus interface for an interconnection bus which communicates with the memory controller. The memory controller responsively updates an accumulated count value stored in system memory using the current count value, e.g., incrementing the accumulated count value. A count value can be sent with a pointer to a memory location and an instruction on how the location is to be updated. The instruction may be an atomic read-modify-write operation, and the memory controller can include a dedicated arithmetic logic unit to carry out that operation. A data harvester can then be used to harvest accumulated count values by reading them from a table in system memory.

Abstract: Systems, methods and computer program products may provide monitoring of software performance on a computer. A method of monitoring software performance in a computer may include marking at least one of a load request and a store request, the marked request including an effective instruction address and an effective data address, recording the effective instruction and data addresses in a processor core and sending the marked request to a memory subsystem. The method may also include receiving a fabric response for the marked request, recording the fabric response in the core and tying the effective instruction and data addresses and the fabric response together in a sample.

Abstract: According to one aspect of the present disclosure a system and computer program product for managing memory access is disclosed. The system includes a plurality of memory controllers each configured to maintain memory databus utilization by a corresponding processor at or below a threshold to maintain memory databus utilization of the system at or below a system threshold. The system also includes a service processor configured to receive memory databus utilization data from the memory controllers and programmed to, in response to determining that memory databus utilization for at least one of the processors is below its threshold, reallocate at least a portion of unused databus utilization from the at least one processor to at least one of the other processors.

Abstract: A dual outcome event monitoring unit comprises a plurality of inputs, and a first counter. Each input is associated with an event and the first counter is a bidirectional counter. The dual outcome event monitoring unit is configured to increment the first counter in response to receiving an indication of the occurrence of a first event of a plurality of events. The first event is designated as an increment event. The dual outcome event monitoring unit is also configured to decrement the first counter responsive to receiving an indication of the occurrence of a second event of a plurality of events. The second event is designated as a decrement event.

Abstract: An indication that an event occurred is received from a processor by a dual outcome event monitoring unit. It is determined whether the event is associated with an increment event or a decrement event. In response to determining that the event is associated with the increment event, an event counter is incremented. The event counter is part of the dual outcome monitoring unit. In response to determining that the event is associated with the decrement event, the event counter is decremented.

Abstract: A computing device identifies a load instruction and store instruction pair that causes a load-hit-store conflict. A processor tags a first load instruction that instructs the processor to load a first data set from memory. The processor stores an address at which the first load instruction is located in memory in a special purpose register. The processor determines where the first load instruction has a load-hit-store conflict with a first store instruction. If the processor determines the first load instruction has a load-hit store conflict with the first store instruction, the processor stores an address at which the first data set is located in memory in a second special purpose register, tags the first data set being stored by the first store instruction, stores an address at which the first store instruction is located in memory in a third special purpose register and increases a conflict counter.

Abstract: During a pipeline stall in an out of order processor, until a next to complete instruction group completes, a monitoring unit receives, from a completion unit of a processor, a next to finish indicator indicating the finish of an oldest previously unfinished instruction from among a plurality of instructions of a next to complete instruction group. The monitoring unit receives, from a plurality of functional units of the processor, a plurality of finish reports including completion reasons for a plurality of separate instructions. The monitoring unit determines at least one stall reason from among multiple stall reasons for the oldest instruction from a selection of completion reasons from a selection of finish reports aligned with the next to finish indicator from among the plurality of finish reports.

Abstract: A method for an operating system (OS) enabling an application direct control of a performance monitoring unit (PMU) including enabling the PMU to notify the application when a PMU exception occurs without interrupting the OS by controllably encoding a redirect field in an OS accessible control register, and enabling the application to reinitialize the PMU after the PMU exception.

Abstract: Systems, methods and computer program products may provide monitoring of software performance on a computer. A method of monitoring software performance in a computer may include marking at least one of a load request and a store request, the marked request including an effective instruction address and an effective data address, recording the effective instruction and data addresses in a processor core and sending the marked request to a memory subsystem. The method may also include receiving a fabric response for the marked request, recording the fabric response in the core and tying the effective instruction and data addresses and the fabric response together in a sample.

Abstract: A computing device identifies a load instruction and store instruction pair that causes a load-hit-store conflict. A processor tags a first load instruction that instructs the processor to load a first data set from memory. The processor stores an address at which the first load instruction is located in memory in a special purpose register. The processor determines where the first load instruction has a load-hit-store conflict with a first store instruction. If the processor determines the first load instruction has a load-hit store conflict with the first store instruction, the processor stores an address at which the first data set is located in memory in a second special purpose register, tags the first data set being stored by the first store instruction, stores an address at which the first store instruction is located in memory in a third special purpose register and increases a conflict counter.

Abstract: A method and system are disclosed for sampling instructions executing on a computer processor. A computer processor determines a number of times a specified event has occurred within a specified temporal window. The computer processor determines to mark an instruction to be executed for monitoring based on the number of times the specified event has occurred within the temporal window, and in response, the computer processor marks the instruction.