CSC 456 Spring 2012/10a AJ: Difference between revisions
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=Prefetching and Consistency Models= | =Prefetching and Consistency Models= | ||
==Intro== | ==Intro== | ||
While memory consistency models insure instructions are executed in correct order, these models can hinder efficiency. Since consistency models dictate order of execution, prefetching allows operations to complete quicker once their turn comes by bringing the necessarily data closer into the cache before it is needed. | |||
==Methods== | ==Methods== | ||
Revision as of 03:46, 13 April 2012
Prefetching and Consistency Models
Intro
While memory consistency models insure instructions are executed in correct order, these models can hinder efficiency. Since consistency models dictate order of execution, prefetching allows operations to complete quicker once their turn comes by bringing the necessarily data closer into the cache before it is needed.
Methods
Fixed vs. Adaptive Sequential Prefetching
Fixed sequential prefetching refers to prefetching of that occurs at a constant rate over time. Adaptive sequential prefetching, on the other hand, changes the rate of prefetching allowed over time. The prefetching rate is increased/decreased based on the count of successful prefetches. The rate is therefore dependent on workload and application (a start-up process will have a high rate of cold misses). While both methods improve efficiency, adaptive sequential prefetching is the most efficient as well as the most costly.