Mechanism to track all open pages in a dram memory system

Abstract

A system and method is disclosed to track a large number of open pages in a computer memory system. The computer system contains one or more processors each including a memory controller containing a page table, the page table organized into a plurality of rows with each row able to store an address of an open memory page. A RIMM module containing RDRAM devices is coupled to each processor, each RDRAM containing a plurality of memory banks. The page table increases system memory performance by tracking a large number of open memory pages. Associated with the page table is a bank active table that indicates the memory banks in each RDRAM device having open memory pages. The page table enqueues accesses to the RIMM module in a precharge queue resulting from a page miss caused by the address of an open memory page occupying the same row of the page table as the address of the system memory access resulting in the page miss. The page table also enqueues accesses to system memory in a Row-address-select (“RAS”) queue resulting from a page miss caused by a row of the page table not containing any open memory page address. The page table enqueues accesses to system memory resulting in page hits to open memory pages in a Column-address-select (“CAS”) queue. An entry in the precharge queue is then enqueued into the RAS queue. An entry in the RAS queue after completion is enqueued into the CAS Read or CAS Write queue.