Appeal No. 97-2696
Application 08/231,657
virtual memory in a computer system. The logical addresses in
the virtual memory are mapped to the physical memory on an as
needed basis in a page table. In conventional systems, the
page table is cleared in one colossal sweep after all the free
addresses have been used up. The invention carries out the
clearing or sweeping of the used addresses in an incremental,
ongoing manner, to avoid significant delays caused by one
colossal sweep. This is accomplished by the fact that, upon
the occurrence of a regular event such as the allocation of
free addresses to a new thread or program, a limited number of
entries in the page table are examined and those entries that
have already been used and are no longer needed are deleted or
cleared and added back to the list of free entries.
Representative claims 1 and 17 are reproduced as
follows:
1. A method for allocating address space in a virtual
memory system for a computer, comprising the steps of:
maintaining a list of available addresses that are free
to be allocated to a program;
allocating addresses to a program in response to requests
for address space;
recording entries in a page table relating to addresses
that have been allocated;
-2-
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