Cache memory data replacement strategy

A method for caching specified data of a primary storage main memory in an n-way set associative memory with a copy-back update policy, said associative memory comprising a plurality of rows, each row comprising n ways, said method comprising:

• i. selecting a row of said associative memory according to an address of said specified data;
• ii. if at least one of said ways comprises data from a currently open page of said main memory, caching said specified data in a way comprising data from said currently open page and discontinuing said data caching process;
• iii. if none of said n ways of said selected row comprise data from said currently open page of said main memory, performing the steps of:
• selecting a first way of said selected row according to a first predetermined replacement strategy;
• and
• caching said specified data in said first way.

A method for caching specified data of a primary storage main memory in an n-way set associative memory with a copy-back update policy, said associative memory comprising a plurality of rows, each row comprising n ways, associative data storage, said method comprising:

• selecting a row of said associative memory according to an address of said specified data;
• if a first way of said selected row comprises invalid data, caching said specified data in said first way and discontinuing said data caching process;
• and
• if all of said n ways of said selected row comprise valid data, performing the steps of:
• i. analyzing said main memory to determine a main memory status, including determining a currently open page of said main memory;
• ii. selecting a second way of said selected row for caching in accordance with said main memory status;
• and
• iii. caching said specified data in said second way.

A way selector system, comprising a way selector for selecting a way for the caching of specified data of a primary storage main memory in an n-way set associative memory with a copy-back update policy, said associative memory comprising a plurality of rows, each row comprising n ways, wherein said associative memory comprises a fast memory for caching main memory data for easy external access, and wherein said specified data for caching originates from said main memory and from external agents connected to said main memory via said associative memory, said way selector comprising:

• an invalid data detector, for detecting a way of a selected row comprising invalid data;
• a replacement selector, for selecting a way of said selected row according to a first predetermined replacement strategy;
• an open page identifier, for identifying a way of said selected row comprising data from a currently open page of a main memory;
• and
• an analyzer, associated with said invalid data detector, said replacement selector, said modified data detector, and said open page identifier, for choosing one of said n ways for data replacement.

A way selector system, comprising a way selector for selecting a way for the caching of specified data of a primary storage main memory in an n-way set associative memory with a copy-back update policy, said associative memory comprising a plurality of rows, each row comprising n ways, wherein said associative memory comprises a fast memory for caching main memory data for easy external access, and wherein said specified data for caching originates from said main memory and from external agents connected to said main memory via said associative memory, said way selector comprising:

• an open page identifier, for identifying a way of a selected row comprising data from a currently open page of said main memory;
• a replacement selector, for selecting a way of said selected row according to a predetermined replacement strategy;
• and
• an analyzer, associated with said replacement selector and said open page identifier, for choosing one of said n ways for data replacement.

A method for caching specified data of a primary storage main memory in an n-way set associative memory with a copy-back update policy, said associative memory comprising a plurality of rows, each row comprising n ways, said method comprising:

• selecting an application-specific first replacement strategy;
• selecting a row of said associative memory according to an address of said specified data;
• if a first way of said selected row comprises invalid data, caching said specified data in said first way and discontinuing said data caching process;
• and
• if all of said n ways of said selected row comprise valid data, performing the steps of:
• i. selecting a second way of said selected row according to said first replacement strategy;
• ii. if said second way comprises unmodified data, caching said specified data in said second way and discontinuing said data caching process;
• iii. if said second way comprises modified data, and if at least one of said ways comprises data from a currently open page of said main memory, caching said specified data in a way comprising data from said currently open page and discontinuing said data caching process;
• and
• iv. if said second way comprises modified data, and if none of said n ways of said selected row comprise data from said currently open page of said main memory, caching said specified data in said second way.