Using hardware counters to estimate cache warmth for process/thread schedulers
First Claim
1. A method for operating a computer system comprising the steps of:
- (a) mathematically modeling cache warmth responsive to a hardware counter of a processor in the system;
(b) computing a nominal lifetime of a cache line based upon said model; and
(c) manipulating the state of the system based upon the lifetime.
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Accused Products
Abstract
A method and computer system for estimating cache warmth for thread schedulers in a processor of a multiprocessor system. A mathematical model based upon a Markov Model of queuing theory is used to determine flow probability. The method incorporates data received from cache counters to measure cache hits, cache misses, cache invalidations and cache roll-outs. Based upon the Model and the data received from the counters and the assumption that cache decays exponentially, a nominal lifetime of a cache line is computed and the state of the system is manipulated in accordance with the computed lifetime of the cache line. The method may be applied to either a two way LRU cache or a four way LRU cache for computing an average lifetime of a cache line. Accordingly, cache affinity and thread migration decisions are enhanced thereby providing an efficient method of operating a computer system.
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Citations
37 Claims
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1. A method for operating a computer system comprising the steps of:
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(a) mathematically modeling cache warmth responsive to a hardware counter of a processor in the system;
(b) computing a nominal lifetime of a cache line based upon said model; and
(c) manipulating the state of the system based upon the lifetime. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A computer system, comprising:
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multiple processors, each processor having an associated cache;
hardware counters for measuring state of the cache;
means for building a mathematical model for estimating cache warmth, said means being responsive to said hardware counters;
means for manipulating the state of the system based upon said cache warmth estimate;
wherein said means for building said mathematical model comprises computing an average lifetime of a given cache line. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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20. A computer system, comprising:
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multiple processors, each processor having an associated cache;
hardware counters for measuring state of the cache;
a mathematical model for estimating cache warmth, wherein said model is responsive to hardware measurements;
said cache warmth estimate manipulating the state of the system;
wherein said model comprises computing a nominal lifetime of a given cache line. - View Dependent Claims (21, 22, 23, 24, 25, 26)
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27. An article comprising:
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a computer-readable medium having stored thereon computer executable instructions;
means in the medium for obtaining data from a hardware counter;
means for building a mathematical model for estimating cache warmth;
means for computing a nominal lifetime of a cache line based upon said model; and
means in the medium for manipulating the state of the system based upon said cache warmth estimate. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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Specification