Methods and apparatus for control of asynchronous cache
First Claim
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1. A processing system comprising a cache controller for managing requests for data from a cache memory by a processor, the cache controller comprising:
- an access queue comprised of a plurality of access queue registers configured to hold requests for data pending asynchronous retrieval of the requested data from the cache memory;
an exit queue comprised of a plurality of exit queue registers configured to hold the retrieved requested data until released to the processor; and
a plurality of self-clocked state machines operating in one-to-one correspondence with pairs of the access and exit queue registers for the retrieving requested data from the cache memory asynchronously relative to a frequency domain of the cache controller.
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Abstract
A processing system includes a cache controller for managing requests for data from a cache memory by a processor. The cache controller includes an access queue that holds requests for data pending asynchronous retrieval of the requested data from the cache memory, and an exit queue that holds the requested data retrieved from the cache memory until released to the processor. This queuing arrangement allows data lines to be retrieved from cache memory without a pipeline, while latencies are minimized.
37 Citations
17 Claims
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1. A processing system comprising a cache controller for managing requests for data from a cache memory by a processor, the cache controller comprising:
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an access queue comprised of a plurality of access queue registers configured to hold requests for data pending asynchronous retrieval of the requested data from the cache memory;
an exit queue comprised of a plurality of exit queue registers configured to hold the retrieved requested data until released to the processor; and
a plurality of self-clocked state machines operating in one-to-one correspondence with pairs of the access and exit queue registers for the retrieving requested data from the cache memory asynchronously relative to a frequency domain of the cache controller. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A processing system comprising a plurality of processors and a cache memory allocated among the processors, at least one of the processors comprising a cache controller configured to control processor requests for retrieval of data from the cache memory, from which the requested data is retrieved asynchronously relative to a frequency domain of the requesting processor;
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the cache controller comprising an access queue having a plurality of access registers in which a cache memory address of the requested data is placed and an exit queue having a plurality of data return registers in which the requested data is placed when retrieved from the cache memory; and
a plurality of self-clocked state machines operating in one-to-one correspondence with pairs of the access queue and data return registers for retrieving the requested data from the cache memory asynchronously relative to a frequency domain of the cache controller;
wherein the cache controller is further configured to release, to the processor, the retrieved data in the data return register corresponding to an access queue register holding a cache memory address of the retrieved data. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A method for performing data retrieval from a cache memory in a processing system wherein a processor issues requests for data from the cache memory, the method comprising the steps of:
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providing an access queue having a plurality of access registers an exit queue having a plurality of data return registers and a plurality of self-clocked state machines operating in one-to-one correspondence with pairs of the access queue and data return registers;
asynchronously retrieving data requested from the cache memory, said step performed using a one of the plurality of self-clocked state machines;
returning the requested data to one of the data return registers clocked with the processor, said step performed using a reactive synchronizer; and
releasing the returned data to the processor from the one exit queue register. - View Dependent Claims (14, 15, 16, 17)
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Specification