Look-aside buffer LRU marker controller

Claim 2

An improved look-aside buffer in a computer system which has a memory having at least a first type of data and a second type of data stored in a page format, the look-aside buffer being arranged to retain in a selected location at least two real addresses which have been resolved by the system, of pages containing the different types of data, one of said page addresses being indicated as least recently used by a marker and therefore deleted when a further address is resolved by the system, wherein the buffer is accessed by the system with a virtual address to look up the real address, the improvement comprising: data type detection means to detect buffer accesses by the system which occur corresponding to the first type of data; and marker control means coupled to the data type detection means to prevent the least recently used marker from indicating that an address corresponding to the second type of data was least recently used when a first type of real data address is accessed in the buffer by the system such that second type data page addresses are not deleted from the look-aside buffer as a result of resolving a first type data page address.

Claim 3

The look-aside buffer of claim 1 wherein each page of data stored in the memory has an associated virtual address which indicates one look-aside buffer location.

Claim 4

The look-aside buffer of claim 2 wherein several virtual addresses associated with different pages of memory indicate the same look-aside buffer location.

Claim 5

A look-aside buffer apparatus in a computer system which has a memory having at least a first type of data and a second type of data stored in a page format, the computer system providing a virtual address which must be translated to provide a real address to access the memory, the apparatus comprising: buffer means, arranged to retain in a location at least two real addresses of memory pages as previously resolved by the system, for receiving and translating virtual addresses, each virtual address identifying a corresponding real address; a least recently used marker for indicating which of the addresses in the buffer means was least recently used; data type detection means for detecting buffer translations of virtual addresses corresponding to the first type of data; and marker control means coupled to the data type detection means for preventing the least recently used marker from indicating that an address corresponding to the second type of data was least recently used when a first type of data address is translated by the buffer means such that second type data page addresses are not removed from the buffer means as a result of the computer system resolving a first type data page address.

Claim 6

A look-aside buffer apparatus in a computer system which has a memory having at least a first type of data and a second type of data stored in a page format, the computer system providing a virtual address which must be translated to provide a real address to access the memory, the apparatus comprising: buffer means, arranged to retain in a location at least two real addresses of memory pages as previously resolved by the system, for receiving and translating virtual addresses, each virtual address identifying a corresponding real address; a least recently used marker for indicating which of the addresses in the buffer means was least recently used; data type detection means for detecting buffer translations of virtual addresses corresponding to the first type of data; and marker control means coupled to the data type detection means for preventing the least recently used marker from indicating that an address corresponding to the second type of data was least recently used when a first type of data address is translated by the buffer means such that second type data page addresses are not removed from the buffer means as a result of the computer system resolving a first type data page address.

Claim 7

The apparatus of claim 4 wherein the first type of data comprises instructions for execution by the computer system.

Claim 8

The apparatus of claim 5 wherein the second type of data comprises data for use in execution of instructions.

Claim 9

The look-aside buffer of claim 6 wherein certain instructions require two real addresses of the second type of data in a single look-aside buffer location.

Claim 10

The apparatus of claim 7 wherein the marker control means does not change the least recently used marker upon the occurance of an instruction address translation made by said buffer means.

Claim 11

The apparatus of claim 5 wherein the buffer means further comprises at least a first and a second virtual address of memory pages in each location identifying at least a first and a second real address of memory pages respectively.

Claim 12

The apparatus of claim 9 and further comprising compare means coupled to the buffer means for first comparing the virtual address provided by the computer system with one of the first and second virtual addresses in the location specified by the virtual address provided by the computer system and then comparing the virtual address provided by the computer system with the other of the first and second virtual addresses in the location specified by the virtual address provided by the computer system.

Claim 13

The apparatus of claim 10 wherein the least recently used marker determines which of the first and second virtual addresses in the buffer means is first compared with the virtual address provided by the computer system.

Claim 14

The apparatus of claim 9 wherein the least recently used marker for each location is stored in the buffer means at each location.

Claim 15

The apparatus of claim 12 wherein the least recently used marker for each location is stored with the first and second real addresses.

Claim 16

The apparatus of claim 13 and further comprising writing means coupled to the buffer means and to the marker control means for writing the first and second real addresses and the least recently used marker back to the buffer means location indicated by the virtual address provided by the computer system responsive to the marker control means.

Claim 17

The apparatus of claim 14 wherein the marker control means provides a first type data translation signal to the writing means to prevent the writing means fron writing the least recently used marker back to the buffer means location such that the least recently used marker is not changed in response to a first type data address translation by the buffer means.