Abstract: Asynchronously traversing a disjoint linked data structure is presented. A synergistic processing unit (SPU) includes a handler that works in conjunction with a memory flow controller (MFC) to traverse a disjoint linked data structure. The handler compares a search value with a node value, and provides the MFC with an effective address of the next node to traverse based upon the comparison. In turn, the MFC retrieves the corresponding node data from system memory and stores the node data in the SPU's local storage area. The MFC stalls processing and sends an asynchronous event interrupt to the SPU which, as a result, instructs the handler to retrieve and compare the latest node data in the local storage area with the search value. The traversal continues until the handler matches the search value with a node value or until the handler determines a failed search.

Abstract: A cache manager receives a request for data, which includes a requested effective address. The cache manager determines whether the requested effective address matches a most recently used effective address stored in a mapped tag vector. When the most recently used effective address matches the requested effective address, the cache manager identifies a corresponding cache location and retrieves the data from the identified cache location. However, when the most recently used effective address fails to match the requested effective address, the cache manager determines whether the requested effective address matches a subsequent effective address stored in the mapped tag vector. When the cache manager determines a match to a subsequent effective address, the cache manager identifies a different cache location corresponding to the subsequent effective address and retrieves the data from the different cache location.

Abstract: An application thread executes a direct branch instruction that is stored in an instruction cache line. Upon execution, the direct branch instruction branches to a branch descriptor that is also stored in the instruction cache line. The branch descriptor includes a trampoline branch instruction and a target instruction space address. Next, the trampoline branch instruction sends a branch descriptor pointer, which points to the branch descriptor, to an instruction cache manager. The instruction cache manager extracts the target instruction space address from the branch descriptor, and executes a target instruction corresponding to the target instruction space address. In one embodiment, the instruction cache manager generates a target local store address by masking off a portion of bits included in the target instruction space address. In turn, the application thread executes the target instruction located at the target local store address accordingly.

Abstract: A method for computing includes executing a program, including multiple cacheable lines of executable code, on a processor having a software-managed cache. A run-time cache management routine running on the processor is used to assemble a profile of inter-line jumps occurring in the software-managed cache while executing the program. Based on the profile, an optimized layout of the lines in the code is computed, and the lines of the program are re-ordered in accordance with the optimized layout while continuing to execute the program.

Abstract: A system and method for securely restoring software program context is presented. A special purpose processor core is included in a heterogeneous processing environment where each processor can access a shared memory. The isolated special purpose processor core includes an isolated local memory. The isolated special purpose processor core receives an identifier corresponding to the secured program. The identifier is used to read an encrypted context of the secured program from the shared memory. The encrypted context is decrypted using an encryption key. The decrypted context is stored in the isolated special purpose processor core's local memory. The secured program's context integrity is verified by using a persistent security data that is retrieved from a secure location, such as a persistent storage register that can only be accessed when the special purpose processor core is running in isolation mode. If the context is verified, the secured program is executed.

Abstract: A computer system's multiple processors are managed as devices. The operating system accesses the multiple processors using processor device modules loaded into the operating system to facilitate a communication between an application requesting access to a processor and the processor. A device-like access is determined for accessing each one of the processors similar to device-like access for other devices in the system such as disk drives, printers, etc. An application seeking access to a processor issues device-oriented instructions for processing data, and in addition, the application provides the processor with the data to be processed. The processor processes the data according to the instructions provided by the application.

Abstract: A computer implemented method, data processing system, and computer usable code are provided for generation of hardware thermal profiles for a set of processors. Sampling is performed of the thermal states of the set of processors during the execution of a set of workloads to create sampled information. The sampled information and thermal characteristics of the set of processors are combined and a thermal index is generated based on the sampled information and characteristics of the set of processors.

Abstract: A system and method for an efficient implementation of a software-managed cache is presented. When an application thread executes on a simple processor, the application thread uses a conditional data select instruction for eliminating a conditional branch instruction when accessing a software-managed cache. An application thread issues a conditional data select instruction (DMA transfer) after a cache directory lookup, wherein the size of the requested data is dependent upon the outcome of the cache directory lookup. When the cache directory lookup results in a cache hit, the application thread requests a transfer of zero bits of data, which results in a DMA controller (DMAC) performing a no-op instruction. When the cache directory lookup results in a cache miss, the application thread requests a data block transfer the size of a corresponding cache line.

Abstract: Loading software on a plurality of processors is presented. A processing unit (PU) retrieves a file from system memory and loads it into its internal memory. The PU extracts a processor type from the file's header which identifies whether the file should execute on the PU or a synergistic processing unit (SPU). If an SPU should execute the file, the PU DMA's the file to the SPU for execution. In one embodiment, the file is a combined file which includes both PU and SPU code. In this embodiment, the PU identifies one or more section headers included in the file which indicates embedded SPU code within the combined file. In this embodiment, the PU extracts the SPU code from the combined file and DMA's the extracted code to an SPU for execution.

Abstract: A computer implemented method, data processing system, computer usable code, and apparatus are provided for generation of software thermal profiles for applications executing on a set of processors. Sampling is performed of the hardware operations occurring in a set of processors during the execution of a set of workloads to create sampled information. A thermal index is then generated based on the sampled information.

Abstract: Computational load is balanced across a plurality of processors. Source code subtasks are compiled into byte code subtasks whereby the byte code subtasks are translated into processor-specific object code subtasks at runtime. The processor-type selection is based upon one of three approaches which are 1) a brute force approach, 2) higher-level approach, or 3) processor availability approach. Each object code subtask is loaded in a corresponding processor type for execution. In one embodiment, a compiler stores a pointer in a byte code file that references the location of a byte code subtask. In this embodiment, the byte code subtask is stored in a shared library and, at runtime, a runtime loader uses the pointer to identify the location of the byte code subtask in order to translate the byte code subtask.

Abstract: Grouping processors is presented. A processing unit (PU) initiates an application and identifies the application's requirements. The PU assigns one or more synergistic processing units (SPUs) and a memory space to the application in the form of a group. The application specifies whether the task requires shared memory or private memory. Shared memory is a memory space that is accessible by the SPUs and the PU. Private memory, however, is a memory space that is only accessible by the SPUs that are included in the group. When the application executes, the resources within the group are allocated to the application's execution thread. Each group has its own group properties, such as address space, policies (i.e. real-time, FIFO, run-to-completion, etc.) and priority (i.e. low or high). These group properties are used during thread execution to determine which groups take precedence over other tasks.

Abstract: An approach to hiding memory latency in a multi-thread environment is presented. Branch Indirect and Set Link (BISL) and/or Branch Indirect and Set Link if External Data (BISLED) instructions are placed in thread code during compilation at instances that correspond to a prolonged instruction. A prolonged instruction is an instruction that instigates latency in a computer system, such as a DMA instruction. When a first thread encounters a BISL or a BISLED instruction, the first thread passes control to a second thread while the first thread's prolonged instruction executes. In turn, the computer system masks the latency of the first thread's prolonged instruction. The system can be optimized based on the memory latency by creating more threads and further dividing a register pool amongst the threads to further hide memory latency in operations that are highly memory bound.

Abstract: A computer implemented method, data processing system, computer usable code, and apparatus are provided for optimizing the thermal performance of a computer system. A set of processor cores associated with the computer system are identified. A thermal index is requested for each of the set of processor cores and the processor cores are ranked based on the thermal index. Software is then mapped to execute on an optimal processor core form the set of processor cores based on the ranking.

Abstract: To alleviate at least some of the costs associated with context switching, addition fields, either with associated Application Program Interfaces (APIs) or coupled to application modules, can be employed to indicate points of light weight context during the operation of an application. Therefore, an operating system can pre-empt applications at points where the context is relatively light, reducing the costs on both storage and bus usage.

Abstract: A computer implemented method, data processing system, and computer usable code are provided for optimizing thermal performance of a computer system. Identification of a set of system resources associated with the computer system is performed and a thermal index is requested for each of the set of system resources to form a set of thermal indexes. An action from a set of actions is identified to reduce resource utilization. The action is implemented to reduce a thermal state of the computer system.

Abstract: Code handling, such as interpreting language instructions or performing “just-in-time” compilation, uses a heterogeneous processing environment that shares a common memory. In a heterogeneous processing environment that includes a plurality of processors, one of the processors is programmed to perform a dedicated code-handling task, such as perform just-in-time compilation or interpretation of interpreted language instructions, such as Java. The other processors request code handling processing that is performed by the dedicated processor. Speed is achieved using a shared memory map so that the dedicated processor can quickly retrieve data provided by one of the other processors.

Abstract: Processor resources are partitioned based on memory usage. A compiler determines the extent to which a process is memory-bound and accordingly divides the process into a number of threads. When a first thread encounters a prolonged instruction, the compiler inserts a conditional branch to a second thread. When the second thread encounters a prolonged instruction, a conditional branch to a third thread is executed. This continues until the last thread conditionally branches back to the first thread. An indirect segmented register file is used so that the “return to” and “branch to” logical registers within each thread are the same (e.g., R1 and R2) for each thread. These logical registers are mapped to hardware registers that store actual addresses. The indirect mapping is altered to bypass completed threads. When the last thread completes it may signal an external process.

Abstract: Managing a computer system's multiple processors as devices. The operating system accesses the multiple processors using processor device modules loaded into the operating system to facilitate a communication between an application requesting access to a processor and the processor. A device-like access is determined for accessing each one of the processors similar to device-like access for other devices in the system such as disk drives, printers, etc. An application seeking access to a processor issues device-oriented instructions for processing data, and in addition, the application provides the processor with the data to be processed. The processor processes the data according to the instructions provided by the application.

Abstract: A method for an asymmetric heterogeneous multi-threaded operating system is presented. A processing unit (PU) provides a trusted mode environment in which an operating system executes. A heterogeneous processor environment includes a synergistic processing unit (SPU) that does not provide trusted mode capabilities. The PU operating system uses two separate and distinct schedulers which are a PU scheduler and an SPU scheduler to schedule tasks on a PU and an SPU, respectively. In one embodiment, the heterogeneous processor environment includes a plurality of SPUs. In this embodiment, the SPU scheduler may use a single SPU run queue to schedule tasks for the plurality of SPUs or, the SPU scheduler may use a plurality of run queues to schedule SPU tasks whereby each of the run queues correspond to a particular SPU.