International Business Machines Corporation

Richard E Fry

Eric Eugene Retter

Kenneth Lee Wright

Marc Avery Gollub

Troy N Hicks

Dung Q Nguyen

Luis Alfonso Lastras-Montano

Larry Edward Thatcher

James Edward Phillips

Andrew Augustus Bjorksten

Albert Thomas Williams

Duc Quang Bui

A method and apparatus for controlling marking store updates in a central electronic complex with a plurality of core processors and eDRAM cache and interconnect bus to a service processor for loading memory controller firmware to dual-channel DDR3 memory controllers with an internal marking store. Loaded firmware of the memory controllers is responsible for tracking of ECC errors using a ECC decoder control whereby said marking store is written by a slow ECC decoder, and read by a fast ECC decoder for every read operation of said memory controllers to provide a blocking mechanism for notifying marking store firmware when the marking store has been updated and which guarantees that marking store firmware cannot write to the marking store until the marking store firmware has seen updates without causing the marking store hardware to time out.

Computer system and method of protection for the system's marking store

A method and circuit for implementing enhanced memory reliability using memory scrub operations to determine a frequency of intermittent correctable errors, and a design structure on which the subject circuit resides are provided. A memory scrub for intermittent performs at least two reads before moving to a next memory scrub address. A number of intermittent errors is tracked where an intermittent error is identified, responsive to identifying one failing read and one passing read of the at least two reads.

Implementing enhanced memory reliability using memory scrub operations

An apparatus for integer exception register (XER) renaming and methods of using the same are implemented. In a central processing unit (CPU) having a pipelined architecture, integer instructions that use or update the XER may be executed out-of-order using the XER renaming mechanism. Any instruction that updates the XER has an associated instruction identifier (IID) stored in a register. Subsequent instructions that use data in the XER use the stored IID to determine when the XER data has been updated by the execution of the instruction corresponding to the stored IID. As each instruction that updates XER data is executed, the data is stored in an XER rename buffer. Instructions using XER data then obtain the updated, valid, XER data from the rename buffer. In this way, these instructions can obtain valid XER data prior to completion of the preceding instructions. The XER data is retrieved from the XER rename buffer by indexing into the buffer by using an index derived from the stored IID. Because the updated XER data is available in the rename buffer before the updating instruction completes, out-of-order execution of instructions using or updating XER data is thereby realized.

Data processing system having an apparatus for exception tracking during

A method and system for interchanging operands and loading such operands into a plurality of operand registers in an execution unit with the data processing system during execution of a complex instruction. A plurality of operands are stored within a register file, including a first operand and a second operand. An instruction is loaded into the first stage of the execution pipe within the execution unit, wherein the instruction has a plurality of fields. Such fields include a first and second field, containing a first and second operand pointer, respectively, for designating a value stored in the register file for loading into first and second operand registers, respectively. Next, the first and second operand pointers are interchanged between the first and second fields. Finally, the first operand register is loaded with the value in the register file designated by the second operand pointer stored in the first field, and the second operand register is loaded with the value in the register file designated by the first operand pointer in the second field, wherein the values in the register file designated by operand pointers in the fields of the instruction are loaded into different operand registers than originally specified by the instruction, thereby facilitating execution of a complex instruction in the execution unit.

Method and system for interchanging operands during complex instruction

A system that allows the continuous accessing of data on a floating point processor unit (FPU), by providing two data ports and corresponding buses between the data cache and the FPU. Further, synchronization between the fixed point unit (FXU), which provides the addresses, and the FPU is provided so that data can be loaded in the event of a data cache miss. This synchronization allows data to be transferred from the DCU to the FPU independent of an error condition (cache miss) on one of the buses. If a cache miss occurs that affects a first one of the buses, then the instruction corresponding to this data is held. Subsequent floating point data is received by the FPU on the second bus not subject to the miss. Synchronization signals include, load ready (LD1.sub.-- RDY) indicating to the FPU that data is on the bus and ready to be moved to the FPU and load not ready (LD1.sub.-- NRDY) that means a floating point load has executed successfully in the FXU, but due to a cache miss, the data is not yet available to the FPU. The FXU sends an address, along an address bus corresponding to the data bus not affected by the miss, for data in the cache. Thus, even in the case of a data cache miss, the FPU can continue operations by loading data, that has been addressed to the data port which does not correspond to the cache miss.

Synchronization for out of order floating point data loads

A data processing system is provided that includes a plurality of execution units each including independent circuits for storing and executing instructions. A circuit is also included for providing instructions from a sequence of instructions to the execution units where each instruction is provided to only one of the execution units. The system includes a circuit for detecting when an instruction in a first execution unit must complete execution prior to execution of an instruction in a second execution unit to produce correct results. A circuit is further included, responsive to the circuit for detecting, for delaying executing the instruction in the second execution unit until the instruction in the first execution unit has completed execution.

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Round Rock, TX, United States of America

Richard E Fry