Memory system performing cache bypassing operation and cache management method thereof

A method for managing a cache memory included in a buffer die of a high-bandwidth memory, the method comprising:

• receiving a cache request from a processor;
• determining a cache miss based on a set index and a tag information included in the cache request;
• identifying whether an invalid line or a clean line exists among cache lines associated with the set index, when the cache miss has been determined;
• and
• when the invalid line or the clean line does not exist, writing cache requested data to the high-bandwidth memory by bypassing the cache memory and transferring the cache requested data to the processor from the high-bandwidth memory.

A memory system, comprising:

• a memory device configured to store or output data according to an access command;
• a processor configured to generate the access command for the memory device;
• and
• a cache memory configured to provide a cache function to the processor and configured to manage a plurality of cache lines according to a cache replacement policy,
• wherein when an invalid line and a clean line do not exist in the plurality of cache lines after a cache miss, the cache memory is configured to perform a cache bypassing operation to directly access the memory device without replacing a cache in response to a cache read request or cache write request from the processor.