Sun Microsystems, Inc.

Poonacha P Kongetira

Sanjay Patel

David J Greenhill

Daniel Lawrence Leibholz

Shree Kant

Kathirgamar Aingaran

Kenway W Tam

Julie M Staraitis

Marc E Lamere

Zhen Wu Liu

Yuan-Jung D Lin

Micah C Knapp

Richard H Larson

Miriam G Blatt

Vidyasagar Ganesan

A memory system includes an active storage circuit and at least one base storage circuit. The at least one base storage circuit is coupled to the active storage circuit though at least one pass gate, at least one driver and a bit line. The at least one pass gate and the at least one driver have a device size substantially similar to a device size of each one of the devices in the active storage circuit and the at least one base storage circuit. A method of swapping data between two storage circuits is also described.

Efficient method of data transfer between register files and memories

A method for modeling the power behavior of a pipelined processor has been developed. The method uses a power model integrated into a cycle accurate simulator. To create the power model, design blocks of the processor are divided into sub-blocks. Power modeling equations for each sub-block are developed by collaboration between the sub-block circuit designer and the simulator developer, using activity information relevant to the sub-block that is available in the simulator model. Each equation is calculated multiple times with different sets of power parameters to represent varying power conditions. Every simulation cycle, sub-block power is summed to generate full-chip power for multiple power conditions.

Power modeling methodology for a pipelined processor

A superscalar processor having a content addressable memory structure that transmits a first and second output signal is presented. The superscalar processor performs out of order processing on an instruction set. From the first output signal, the dependencies between currently fetched instructions of the instruction set and previous in-flight instructions can be determined and used to generate a dependency matrix for all in-flight instructions. From the second output signal, the physical register addresses of the data required to execute an instruction, once the dependencies have been removed, may be determined.

Superscalar processor having content addressable memory structures for determining dependencies

One embodiment of the present invention provides a system that selects instructions to be executed in a computer system that supports out-of-order execution of program instructions. The system receives dependency information for a first instruction. This dependency information identifies preceding instructions in the execution stream of a program that need to complete before the first instruction can be executed. The system divides this dependency information into a recent set and a less recent set. The recent set includes dependency information for a block of instructions immediately preceding the first instruction that need to complete before the first instruction can be executed. The less recent set includes dependency information for instructions not in the block of instructions immediately preceding the first instruction that need to complete before the first instruction can be executed. The system stores the recent set of dependency information in a first store, and stores the less recent set of dependency information in a second store. The first store is smaller and faster than the second store so that an update to dependency information takes less time to propagate through the first store than the second store. In one embodiment of the present invention, the system receives the dependency information for the first instruction from the first store and the second store, and determines from the dependency information if the first instruction is available to be executed by determining whether all preceding dependencies related to the first instruction have been satisfied. In one embodiment of the present invention, the system selects a second instruction from instructions that are available to be executed, and executes the second instruction.

Instruction dependency scoreboard with a hierarchical structure

A unified array access for two logically different arrays is provided. The first array includes CAM cells arranged in n rows and x columns. At least one CAM cell is coupled to a match line, a CAM word line, and to a CAM bit line. The second array includes first RAM cells arranged in n rows and y columns and second RAM cells arranged in n rows and z columns. At least one first RAM cell is coupled to a RAM word line, and to a first RAM bit line. At least one second RAM cell is coupled to the same RAM word line, and a second RAM bit line. RAM word line drivers are provided to activate the first and second RAM cells during a read or write access thereof. At least one RAM word driver has an output coupled to first and second RAM cells. N match sense amplifiers are provided, at least one of which has an input coupled to one of the CAM cells via a match line, and an output coupled to at least one RAM word driver. Y first RAM driver circuits are provided, at least one of which has a first output coupled to the first RAM bit line, a first input configured to receive a first data input signal, and a control input configured to receive a first RAM write enable signal. The first RAM write driver circuit is configured to charge the first RAM bit line in response to receiving the first RAM write enable signal. The second RAM write driver circuits are also provided, at least one of which has a second output coupled to the RAM bit line, a second input configured to receive a second data input signal, and a control input configured to receive a second RAM write enable signal. The second RAM write driver circuit is configured to charge the second RAM bit line in response to receiving the second write enable signal. Moreover, the second RAM write driver circuit is configured to operate independently from the first RAM write driver circuit.

Translation look aside buffer having separate RAM arrays which are

A single-ended match sense amplifier is provided for use in a translation lookaside buffer. The translation lookaside buffer includes a CAM array for storing x bit virtual addresses. The CAM array has n rows and x columns of CAM cells, each CAM cell having input node for receiving a virtual address bit signal, and a CAM miss/match node. N rows and minor sense amplifier circuits are coupled to n major sense amplifier circuits via n major sense lines. Each minor sense amplifier circuit has a minor sense input node, and a minor sense miss/match node. Each minor sense line is also coupled to at least two CAM cell miss/match nodes. A minor sense precharging device is coupled to each minor sense line. The minor sense precharging device selectively conducts current to precharge the minor sense lines to a first predetermined voltage. Each of the major sense amplifiers has a major sense input node, and a major sense miss/match node. Each major sense line is coupled to at least two minor sense miss/match nodes and one major sense input node. Major sense precharging devices are coupled to each major sense line. The major sense precharging devices selectively conduct current to precharge the major sense lines to the first predetermined voltage.

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Menlo Park, CA, United States of America

Poonacha P Kongetira