I/WE CLAIM:
1. An apparatus comprising:
a plurality of threshold registers to store respective voltage droop thresholds;
an interface to receive a license grant message indicating a license mode for a processor core or domain, the license mode corresponding to a selected set of execution units in the processor core or domain; a voltage droop correction module to:
based on the license mode indicated in the license grant message, select one of the voltage droop thresholds from the plurality of voltage droop registers;
compare a voltage droop in the processor core or domain with the selected voltage droop threshold; and
based on the comparison, trigger a voltage droop correction process.
2. The apparatus of claim 1, further comprising a voltage regulator to
couple a regulated voltage to a device including the processor core or
domain.
3. The apparatus of claim 2, wherein the voltage regulator is coupled to a motherboard.
4. The apparatus of claim 2, wherein the voltage regulator comprises a fully integrated voltage regulator (FIVR) integrated with the device including the processor core or domain.

5. The apparatus of claim 1, wherein the interface receives the license grant message from a power control unit (PCU).
6. The apparatus of claim 1, wherein the voltage droop correction process comprises a non-linear control process to provide excess current to the processor core or domain via one or more current supply lines.
7. The apparatus of claim 6, wherein the voltage droop correction module further comprises one or more current clamps configured to provide the excess current to the one or more current supply lines in response to the trigger.
8. The apparatus of claim 7, wherein the voltage droop correction module further comprises:
a threshold selector module coupled to the plurality of threshold register, the threshold selector module configured to, based on the license mode indicated in the license grant message, select one of the voltage droop thresholds from the plurality of voltage droop registers;
a voltage sense line coupled to an area of the processor core or domain expected to experience the voltage droop; and
a comparator to compare a sensed voltage droop on the voltage sense line to the selected voltage droop threshold to detect a droop event, and to fire the one or more current clamps in response to the detected droop event.
9. The apparatus of claim 8, wherein the voltage sense line comprises
a first voltage sense line, the area of the processor core or domain comprises
a first area of the processor core or domain, the comparator comprises a first
comparator, the sensed voltage droop comprises a first sensed voltage

droop, and the droop event comprises a first droop event, wherein the voltage droop correction module further comprises:
a second voltage sense line coupled to a second area of the processor core or domain expected to experience the voltage droop; and
a second comparator to compare a second sensed voltage droop on the second voltage sense line to the selected voltage droop threshold to detect a second droop event, and to fire the one or more current clamps in response to the detected second droop event.
10. The apparatus of claim 8, wherein the voltage droop correction module further comprises a digital to analog converter coupled between the threshold selector module and the comparator, wherein the selected voltage droop threshold comprises a digital value, and wherein the digital to analog converter is configured to convert the digital value to an analog threshold signal and to provide the analog threshold signal to an input of the comparator.
11. The apparatus of claim 7, wherein the voltage droop correction module is configured to adjust a strength of the one or more current clamps based on the license mode indicated in the license grant message.
12. A method comprising:
receiving, at a voltage regulator, a signal indicating a license mode corresponding to a selected set of execution units in a core or domain of a processor;
based on the indicated license mode, selecting one of a plurality of thresholds;
detecting a voltage droop event in the core or domain of the processor;

determining that the voltage droop event exceeds the selected threshold; and
in response to the determination, triggering a voltage droop correction process.
13. The method of claim 12, wherein the voltage droop correction process comprises a non-linear control process including providing excess current to the processor core or domain via one or more current supply lines.
14. The method of claim 13, wherein triggering the voltage droop correction process comprises triggering one or more current clamps configured to provide the excess current to the one or more current supply lines.
15. The method of claim 14, further comprising adjusting a strength of the one or more current clamps based on the license mode indicated in the license grant message.
16. The method of claim 13, wherein triggering the voltage droop correction process comprises adjusting, based on the license mode indicated in the license grant message, a strength of one or more current clamps configured to provide the excess current.
17. The method of claim 12, wherein detecting the voltage droop event comprises receiving a signal from a voltage sense line coupled to an area of the processor core or domain expected to experience the voltage droop.

18. At least one computer-readable storage medium having stored
thereon instructions that, when executed by a processor, cause the processor
to perform operations comprising:
receiving a signal indicating a license mode corresponding to a selected set of execution units in a core or domain;
based on the indicated license mode, selecting one of a plurality of thresholds;
detecting a voltage droop event in the core or domain;
determining that the voltage droop event exceeds the selected threshold; and
in response to the determination, triggering a voltage droop correction process.
19. The at least one computer-readable storage medium of claim 18, wherein the voltage droop correction process comprises a non-linear control process including providing excess current to the processor core or domain via one or more current supply lines.
20. The at least one computer-readable storage medium of claim 19, wherein triggering the voltage droop correction process comprises triggering one or more current clamps configured to provide the excess current to the one or more current supply lines.
21. The at least one computer-readable storage medium of claim 20, further comprising adjusting a strength of the one or more current clamps based on the license mode indicated in the license grant message.
22. The at least one computer-readable storage medium of claim 19, wherein triggering the voltage droop correction process comprises adjusting,

based on the license mode indicated in the license grant message, a strength of one or more current clamps configured to provide the excess current.
23. A processor comprising:
a plurality of cores each to independently execute instructions and to operate at independent voltages and frequencies; and
one or more integrated voltage regulators to provide the independent voltages and frequencies to the plurality of cores, wherein each of the one or more voltage regulators comprises:
a storage device to store a plurality of voltage droop thresholds; an interface to receive, from a power control unit, a license grant message indicating a license mode for corresponding core of the plurality of cores, the license mode corresponding to a selected set of execution units; and
a voltage droop correction module to:
based on the license mode indicated in the license grant message, select one of the plurality of voltage droop thresholds;
compare a voltage droop in the corresponding core with the selected voltage droop threshold; and
based on the comparison, trigger a voltage droop correction process.
24. The processor of claim 23, wherein the voltage droop correction process comprises a non-linear control process to provide excess current to the corresponding core via one or more current supply lines.
25. The processor of claim 24, wherein the voltage droop correction module further comprises:

one or more current clamps configured to provide the excess current to the one or more current supply lines in response to the trigger.
a threshold selector module to, based on the license mode indicated in the license grant message, select one of the plurality of voltage droop thresholds;
a voltage sense line coupled to an area of the corresponding core expected to experience the voltage droop; and
a comparator to compare a sensed voltage droop on the voltage sense line to the selected voltage droop threshold to detect a droop event, and to fire the one or more current clamps in response to the detected droop event.