Abstract:
A system including a host coupled to a serially connected chain of memory modules. In one embodiment, each of the memory modules includes a memory control hub for controlling access to a plurality of memory chips on the memory module. The memory modules are coupled serially in a chain to the host via a plurality of memory links. Each memory link may include an uplink for conveying transactions toward the host and a downlink for conveying transactions originating at the host to a next memory module in the chain. The uplink and the downlink may convey transactions using packets that include control and configuration packets and memory access packets. The memory control hub may convey a transaction received on a first downlink of a first memory link on a second downlink of a second memory link independent of decoding the transaction.
Abstract:
A microprocessor configured to rapidly execute floating point store status word (FSTSW) type instructions that are immediately preceded by floating point compare (FCOM) type instructions is disclosed. FCOM-type instructions are modified to store their results to an architectural floating point status word and a temporary destination register. If an FSTSW-type instruction is detected immediately following an FCOM-type instruction, then the FSTSW-type instruction is transformed into a special fast floating point store status word (FSTSWEF) instruction. Unlike the FSTSW-type instruction, which is serializing and negatively impacts performance, the FSTSWEF instruction is not serializing and allows execution to continue without undue serialization. A computer system and method for rapidly executing FSTSW instructions immediately preceded by FCOM-type instructions are also disclosed.
Abstract:
A multiplier capable of performing signed and unsigned scalar and vector multiplication is disclosed. The multiplier is configured to receive signed or unsigned multiplier and multiplicand operands in scalar or packed vector form. An effective sign for the multiplier and multiplicand operands may be calculated and used to create and select a number of partial products according to Booth's algorithm. Once the partial products have been created and selected, they may be summed and the results may be output. The results may be signed or unsigned, and may represent vector or scalar quantities. When a vector multiplication is performed, the multiplier may be configured to generate and select partial products so as to effectively isolate the multiplication process for each pair of vector components. The multiplier may also be configured to sum the products of the vector components to form the vector dot product. The final product may be output in segments so as to require fewer bus lines. The segments may be rounded by adding a rounding constant. Rounding and normalization may be performed in two paths, one assuming an overflow will occur, the other assuming no overflow will occur. The multiplier may also be configured to perform iterative calculations to evaluate constant powers of an operand. Intermediate products that are formed may be rounded and normalized in two paths and then compressed and stored for use in the next iteration. An adjustment constant may also be added to increase the frequency of exactly rounded results.
Abstract:
A multimedia extension unit (MEU) is provided for performing various multimedia-type operations. The MEU may be coupled either through a coprocessor bus or a local CPU bus to a conventional processor. The MEU employs vector registers, a vector ALU, and an operand routing unit (ORU) to perform a maximum number of the multimedia operations within as few instruction cycles as possible. Complex algorithms are readily performed by arranging operands upon the vector ALU in accordance with the desired algorithm flowgraph. The ORU aligns the operands within partitioned slots or sub-slots of the vector registers using vector instructions unique to the MEU. At the output of the ORU, operand pairs from vector source or destination registers may be easily routed and combined at the vector ALU. The vector instructions employ special load/store instructions in combination with numerous operational instructions to carry out concurrent multimedia operations on the aligned operands. In one embodiment, an arithmetic logic unit may be partitioned into at least two logic portions. A first logic portion may be coupled to receive a first operand from a fixed slot of a first register and a second operand from any slot of a second register. A second logic portion may be coupled to receive a third operand from a fixed slot of the first register and a fourth operand from any slot of the second register. The first logic portion may perform an arithmetic operation dissimilar from the second logic portion.
Abstract:
A multimedia extension unit (MEU) is provided for performing various multimedia-type operations. The MEU can be coupled either through a coprocessor bus or a local CPU bus to a conventional processor. The MEU employs vector registers, a vector ALU, and an operand routing unit (ORU) to perform a maximum number of the multimedia operations within as few instruction cycles as possible. Complex algorithms are readily performed by arranging operands upon the vector ALU in accordance with the desired algorithm flowgraph. The ORU aligns the operands within partitioned slots or sub-slots of the vector registers using vector instructions unique to the MEU. At the output of the ORU, operand pairs from vector source or destination registers can be easily routed and combined at the vector ALU. The vector instructions employ special load/store instructions in combination with numerous operational instructions to carry out concurrent multimedia operations on the aligned operands. In one embodiment multiple ALUs may each receive one operand from a fixed source register slot location, where the fixed slot location may be different for each ALU. The operand routing may provide another operand from any source register slot location for another input to each respective ALU.
Abstract:
A multimedia extension unit (MEU) is provided for performing various multimedia-type operations. The MEU can be coupled either through a coprocessor bus or a local central processing unit (CPU) bus to a conventional processor. The MEU employs vector registers, a vector arithmetic logic unit (ALU), and an operand routing unit (ORU) to perform a maximum number of the multimedia operations within as few instruction cycles as possible. Complex algorithms are readily performed by arranging operands upon the vector ALU in accordance with the desired algorithm flowgraph. The ORU aligns the operands within partitioned slots or sub-slots of the vector registers using vector instructions unique to the MEU. At the output of the ORU, operand pairs from vector source or destination registers can be easily routed and combined at the vector ALU. The vector instructions employ special load/store instructions in combination with numerous operational instructions to carry out concurrent multimedia operations on the aligned operands.
Abstract:
A digital data processing apparatus has plural processing cells, each with a memory element that stores data page made up of plural subpages. At least one of the cells includes a CPU that can request access to a data subpage. A memory manager responds to selected data access requests by (i) allocating, within the memory local to the requesting CPU, exclusive physical storage space for a data page associated with the requested subpage, and (ii) storing the requested subpage in that allocated space. The apparatus recombines data pages and deallocates them on the basis of usage and access state. The apparatus also accesses data asynchronously with respect to execution of instructions by the CPU.
Abstract:
A computer system with a processor cache that stores remote cache presence information. In one embodiment, a plurality of presence vectors are stored to indicate whether particular blocks of data mapped to another node are being remotely cached. Rather than storing the presence vectors in a dedicated storage, the remote cache presence vectors may be stored in designated locations of a cache memory subsystem, such as an L2 cache, associated with a processor core. For example, a designated way of the cache memory subsystem may be allocated for storing remote cache presence vectors, while the remaining ways of the cache are used to store normal processor data. New data blocks may be remotely cached in response to evictions from the cache memory subsystem. In yet a further embodiment, additional entries of the cache memory subsystem may be used for storing directory entries to filter probe command and response traffic.
Abstract:
A multiplier capable of performing signed and unsigned scalar and vector multiplication is disclosed. The multiplier is configured to receive signed or unsigned multiplier and multiplicand operands in scalar or packed vector form. An effective sign for the multiplier and multiplicand operands may be calculated and used to create and select a number of partial products according to Booth's algorithm. Once the partial products have been created and selected, they may be summed and the results may be output. The results may be signed or unsigned, and may represent vector or scalar quantities. When a vector multiplication is performed, the multiplier may be configured to generate and select partial products so as to effectively isolate the multiplication process for each pair of vector components. The multiplier may also be configured to sum the products of the vector components to form the vector dot product. The final product may be output in segments so as to require fewer bus lines. The segments may be rounded by adding a rounding constant. Rounding and normalization may be performed in two paths, one assuming an overflow will occur, the other assuming no overflow will occur. The multiplier may also be configured to perform iterative calculations to evaluate constant powers of an operand. Intermediate products that are formed may be rounded and normalized in two paths and then compressed and stored for use in the next iteration. An adjustment constant may also be added to increase the frequency of exactly rounded results.
Abstract:
A microprocessor with a floating point unit configured to efficiently allocate multi-pipeline executable instructions is disclosed. Multi-pipeline executable instructions are instructions that are not forced to execute in a particular type of execution pipe. For example, junk ops are multi-pipeline executable. A junk op is an instruction that is executed at an early stage of the floating point unit's pipeline (e.g., during register rename), but still passes through an execution pipeline for exception checking. Junk ops are not limited to a particular execution pipeline, but instead may pass through any of the microprocessor's execution pipelines in the floating point unit. Multi-pipeline executable instructions are allocated on a per-clock cycle basis using a number of different criteria. For example, the allocation may vary depending upon the number of multi-pipeline executable instructions received by the floating point unit in a single clock cycle.