Multi-class data cache policies

Abstract

The present invention provides multi-class data cache policies. An embodiment of the invention clarifies a mechanism for expelling out data from data cache based on the class of data. Based on the data class which reflects the reusing probability, the data stored in the cache lines in the data cache are classified. The data class is stored in a tag memory, wherein each tag in the tag memory is corresponding with a single cache line in the data cache. When the data related with command is stored in the cache, a tag checking unit checks the data class in the tag memory for determining which data are expelled. The data with lower reusing probability is ejected out with a high priority compared with the data with higher reusing probability. Advantageously, the ejection of the data of data class with lower reusing probability reduces the number of cache loss in the system.

Description

technical field [0001] The present invention relates generally to the field of memory management, and more particularly, to multi-class data caching strategies. Background technique [0002] One element of the memory subsystem within a certain processing unit is Level 2 cache memory (referred to herein as "L2 cache"). The L2 cache is a large on-chip memory that serves as an intermediate point between external memory (eg, framebuffer memory) and the memory subsystem's internal clients (referred to herein as "clients"). The L2 cache temporarily stores data being used by various clients. This data can be retrieved from or written to external memory (referred to herein as "DRAM"). The client can reuse the data stored in the L2 cache while performing certain operations. [0003] During a read operation, the client may request data from the L2 cache that is not currently stored in the L2 cache, so this data must be obtained from DRAM. A read operation that must obtain data fro...

AI Technical Summary

Problems solved by technology

However, in certain systems where the usage pattern of the data changes, such an approach may not be sufficient to evict data quickly enough to make room for future read and write operations and to allow data to remain in the cache long enough to Appropriate balance between reusing and avoiding requesting data from external memory

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