Method for reducing translation look aside buffer purges in a multitasking system

摘要

A process for reducing translation look-aside buffer (TLB) purge overhead does so by purging the TLB only when required to avoid invalid entries. The translation look-aside buffer (TLB) contains virtual to real mappings for a particular address space. Operating systems commonly purge the TLB whenever a new task is dispatched to ensure the TLB entries are valid. A system with relatively short tasks will incur significant overhead by this practice. The present invention detects those situations where a purge is required by associating TLB purge with the address space allocation logic. Invalid TLB entries will exist only where an address space is re-used by a different task. The address space allocation logic is modified to place a marker indicating a TLB purge in the queue of free address space blocks. Whenever the marker rises to the head of the queue a TLB purge is issued. Task dispatches at all other times do not require TLB purging.