Dynamic sizing of translation lookaside buffer for power reduction
Methods and mechanisms for operating a translation lookaside buffer (TLB). A translation lookaside buffer (TLB) includes a plurality of segments, each segment including one or more entries. A control unit is coupled to the TLB. The control unit is configured to determine utilization of segments, and dynamically disable segments in response to determining that segments are under-utilized. The control unit is also configured to dynamically enable segments responsive to determining a given number of segments are over-utilized.
1. A processor, comprising:
a translation lookaside buffer (TLB) comprising a plurality of segments, wherein each segment includes one or more entries; and
a control unit coupled to the TLB, wherein the control unit is configured to:
disable an enabled segment in response to determining that the segment is under-utilized; and
enable a disabled segment in response to determining that a given number of currently-enabled segments are over-utilized;
wherein each TLB entry of the one or more entries comprises a corresponding entry access bit; and
wherein each segment of the plurality of segments further comprises a corresponding segment access bit.
2. The processor of claim 1 ,
wherein the control unit is configured to:
determine a particular segment of the plurality of segments is over-utilized, in response to determining a number of active entries in the particular segment meets an upper threshold; and
determine the particular segment of the plurality of segments is under-utilized, in response to determining the number of active entries in the particular segment meets a lower threshold.
3. The processor of claim 1 , wherein the control unit is further configured to enable a disabled segment in response to detecting an event or condition.
4. The processor of claim 3 , wherein the event comprises a TLB miss.
5. The processor of claim 1 wherein the control unit is configured to set an entry access bit of a given entry responsive to at least one of: when the entry is loaded with a translation, and when there is a valid translation match on the entry.
6. The processor of claim 1 , wherein the control unit is further configured to periodically:
set a segment access bit of a first segment if a number of set entry access bits corresponding to the first segment meets an upper threshold;
clear the segment access bit if the number of set entry access bits meets a lower threshold; and
clear all entry access bits.
7. The processor of claim 6 , wherein
a particular segment is considered over-utilized if an access bit corresponding to the particular segment is set or a number of set entry access bits corresponding to the particular segment meets an upper threshold; and
a particular segment is considered under-utilized if the access bit corresponding to the particular segment is not set and the number of set entry access bits corresponding to the particular segment meets a lower threshold.
8. A non-transitory computer readable storage medium comprising instructions, wherein the instructions are executable by a processor to:
access a translation lookaside buffer (TLB) comprising a plurality of segments, wherein each segment includes one or more entries;
disable an enabled segment in response to determining that the segment is under-utilized; and
enable a disabled segment in response to determining that a given number of currently-enabled segments are over-utilized;
wherein each TLB entry of the one or more entries comprises a corresponding entry access bit; and
wherein each segment of the plurality of segments further comprises a corresponding segment access bit.
9. The non-transitory storage medium of claim 8 , wherein the instructions are further executable by a processor to:
determine a particular segment of the plurality of segments is over-utilized, in response to determining a number of active entries in the particular segment meets an upper threshold; and
determine the particular segment of the plurality of segments is under-utilized, in response to determining the number of active entries in the particular segment meets a lower threshold.
10. The non-transitory storage medium of claim 8 , wherein the instructions are further executable by a processor to enable a disabled segment in response to detecting an event or condition.
11. The non-transitory storage medium of claim 10 , wherein the event comprises a TLB miss.
12. The non-transitory storage medium of claim 8 , wherein an entry access bit is set responsive to at least one of: when an entry is loaded with a translation, and when there is a valid translation match to an entry.
13. The non-transitory storage medium of claim 8 , wherein the instructions are further executable by a processor to:
set a segment access bit of a first segment if a number of set entry access bits corresponding to the first segment meets an upper threshold;
clear the segment access bit if the number of set entry access bits meets a lower threshold; and
clear all entry access bits.
14. The non-transitory storage medium of claim 13 , wherein
a particular segment is considered over-utilized if an access bit corresponding to the particular segment is set or a number of set entry access bits corresponding to the particular segment meets an upper threshold; and
a particular segment is considered under-utilized if the access bit corresponding to the particular segment is not set and the number of set entry access bits corresponding to the particular segment meets a lower threshold.
15. A method for managing a translation lookaside buffer (TLB), the method comprising:
accessing a translation lookaside buffer (TLB) comprising a plurality of segments, wherein each segment includes one or more entries;
disabling an enabled segment in response to determining that the segment is under-utilized; and
enabling a disabled segment in response to determining that a given number of currently-enabled segments are over-utilized;
wherein each TLB entry of the one or more entries comprises a corresponding entry access bit; and
wherein each segment of the plurality of segments further comprises a corresponding segment access bit.
16. The method of claim 15 , further comprising:
determining a particular segment of the plurality of segments is over-utilized if a number of active entries in the particular segment meets an upper threshold; and
determining a particular segment of the plurality of segments is under-utilized if a number of active entries in the particular segment meets a lower threshold.
17. The method of claim 15 , further comprising enabling a disabled segment in further response to detecting an event or condition.
18. The method of claim 17 , wherein the event comprises a TLB miss.