Intel Corporation

Sundaravarathan R Iyengar

James Nadir

Devadatta V Bodas

Russell Jerome Fenger

James Steven Burns

Baskaran Ganesan

Suresh Sugumar

Feranak Nelson

Mustafiz R Choudhury

John M Powell, Jr

John H Crawford

Dheemanth Nagaraj

Tsan-Kuen Wang

James F McKevitt, Iii

Murali S Talwai

In one embodiment, a processor has multiple cores to execute threads. The processor further includes a power control logic to enable entry into a turbo mode based on a comparison between a threshold and value of a counter that stores a count of core power and performance combinations that identify turbo mode requests of at least one of the threads. In this way, turbo mode may be entered at a utilization level of the processor that provides for high power efficiency. Other embodiments are described and claimed.

Increasing power efficiency of turbo mode operation in a processor

Systems and methods of operating a computing system may involve identifying a plurality of state values, wherein each state value corresponds to a computing thread associated with a processor. An average value can be determined for the plurality of state values, wherein a determination may be made as to whether to grant a frequency boost request based at least in part on the average value.

Efficient frequency boost operation

A computer system includes a microprocessor having an internal cache memory and control unit that performs write-back operations to external memory responsive to an external signal indicating that a valid external address has been driven onto the address pins of the microprocessor. Under control of a state machine control, a unit within the microprocessor provides an indication signal to the external component that a current write cycle is a write-back cycle; this enables the system to distinguish between an ongoing write cycle generated by the processor, and a new write-back cycle. An additional signal is generated by the microprocessor in the event that the external address indicates a cache hit to a modified line.

Identification of the distinction between the beginning of a new write

A cache controller tag random access memory (RAM) is configured into two ways, each way including tag and valid-bit storage for associatively searching a directory for cache data-array addresses. The two ways, a right way and a left way, each store tag addresses. There are two lines selected during a line fill to one of the ways. A least recently used (LRU) pointer selects which way to fill on a line fill cycle. The right way is selected for a line fill in response to right hit signal provided that the LRU pointer points to the right way. The LRU pointer is flipped to point to the left way upon the filling of the right line of the right way. The left way is selected for a line fill in response to a left hit signal provided that the LRU pointer points to the left way. The LRU pointer is flipped to point to the right way upon the filling of the left line of the left way.

LRU pointer updating in a controller for two-way set associative cache

A processor capable of selecting between a write-back and a write-through mode of operation includes a bus interface unit for transferring information across the external bus. A local cache memory is coupled to the bus interface unit for storing information received from the bus interface unit. The processor also includes a control unit coupled to the cache memory and the bus interface unit. The control unit is operable to restart an interrupted operation from a point of interruption. A storage device coupled to the control unit stores a value corresponding to the point of interruption of the operation.

Method and apparatus for selecting a mode for updating external memory

A processor for processing information is described. The processor can select between a write-burst mode of transferring information and an individual write cycle mode of transferring information. The write-burst mode of transferring information is a transfer of information in a single burst transaction and the individual write cycle mode of transferring information is a transfer of information in separate write cycles.

System and method having processor with selectable burst or no-burst

Apparatus and method for updating LRU pointer in a controller for

A processor communicates over a memory bus with a main memory and a cache by asserting an address strobe signal (ADS) to initiate a memory access. The cache includes a cache controller and a tag random access memory (tag RAM). Internal cycles are tracked by a first logic in the tag RAM that responds to an external cycle (EXCYC) signal and asserts an internal cycle (INCYC) signal during a time when a request to the tag RAM is pending. A second logic combines the INCYC signal with the. ADS to generate an address strobe wait (ADSWAIT) signal. A third logic combines the ADSWAIT signal with the ADS to generate an address strobe cycle (ADSCYC) signal. A fourth logic responsive to one of several end-of-cycle signals generates a terminate signal to signify an end of a current cycle. A fifth logic asserts the EXCYC signal in response to the ADSCYC signal and unasserts the EXCYC signal in response to the terminate signal.

Processor cycle tracking in a controller for two-way set associative

A cache controller tag ram is configured into a two ways, each way including tag and valid-bit storage for associatively searching the directory for cache data-array addresses. The two ways, a right way and a left way, each store tag addresses. First means are provided for asserting a flush signal upon the condition that a warm start reset is recognized or a power up condition is recognized. Logic causes all pending write requests to be withdrawn in response to the flush signal. The directory is cleared by setting all valid, write protect and least recently used (LRU) bits to zero in both of the ways. Subsequent write requests use a line fill algorithm to ensure that correct data is written into the directory by choosing which way to select for a line fill after the bits have been cleared.

Tag initialization in a controller for two-way set associative cache

A cache controller (10) which sits in parallel with a microprocessor bus (14, 15, 29) so as not to impede system response in the event of a cache miss. The cache controller tagram (24) is configured into a two ways, each way including tag and valid-bit storage for associatively searching the directory for cache data-array addresses. The external cache memory (8) is organized such that both ways are simultaneously available to a number of available memory modules in the system to thereby allow the way access time to occur in parallel with the tag lookup.

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San Jose, CA, United States of America

Sundaravarathan R Iyengar