Managing and revoking power allocated through bus interfaces

Abstract

The disclosed embodiments provide a system that manages power allocated through a set of bus interfaces on a computer system. During operation, the system obtains a first request for revocable current beyond a reserved current for a first bus interface from the set of bus interfaces, wherein the request is associated with a first device connected to the first bus interface. Next, the system allocates the revocable current to the first bus interface from an extra-current budget for the set of bus interfaces. Upon detecting a connection of a second device that requires non-revocable current over the extra-current budget to a second bus interface from the set of bus interfaces, the system transmits a first notification to the first device to relinquish the revocable current. Finally, the system allocates the non-revocable current to the second device from the relinquished revocable current.

What is claimed is: 
     
         1 . A method for managing power allocated to devices of a computer system, the method comprising:
 obtaining a first request from a first device for a first revocable current beyond a reserved current for a first bus interface, wherein the first device is connected to a computer system through the first bus interface;   allocating the first revocable current based on the first request to the first device from an extra-current budget;   upon detecting a connection of a second device that requires a non-revocable current beyond the extra-current budget, wherein the second device is connected to the computer system through a second bus interface, sending a first notice to the first device to relinquish the first revocable current; and   allocating the non-revocable current to the second device from the extra-current budget,   wherein the extra-current budget corresponds to current available from the computer system exceeding current reserved for the bus interfaces of the computer system.   
     
     
         2 . The method of  claim 1 , further comprising:
 sending a second notice to the first device for renegotiation of revocable current; and   receiving a second request from the first device for a second revocable current.   
     
     
         3 . The method of  claim 2 , further comprising:
 allocating the second revocable current to the first device from the extra-current budget.   
     
     
         4 . The method of  claim 1 , further comprising:
 upon detecting a connection of a third device that requires a third revocable current beyond the extra-current budget, wherein the third device is connected to the computer system through a third bus interface and the third device has a higher priority than the first device, sending a third notice to the first device to relinquish the first revocable current; and   allocating the third revocable current to the third device from the extra-current budget.   
     
     
         5 . The method of  claim 4 , further comprising:
 sending a second notice to the first device for renegotiation of the revocable current;   receiving a second request from the first device for a second revocable current; and   allocating the second revocable current to the first device from the extra-current budget.   
     
     
         6 . The method of  claim 1 , wherein the extra-current budget is based on at least one of:
 a number of the bus interfaces;   the current reserved for the bus interfaces; and   a power-management mode associated with the computer system.   
     
     
         7 . The method of  claim 1 ,
 wherein the first revocable current varies responsive to use of the first device, and   wherein the non-revocable current varies responsive to use of the second device.   
     
     
         8 . A system for managing power allocated to devices of a computer system, the system comprising:
 a communication apparatus configured to generate, for a first device connected to a computer system through a first bus interface, a first request for a first revocable current beyond a reserved current for the first bus interface; and   a management apparatus configured to:
 allocate the first revocable current based on the first request to the first device from an extra-current budget; 
 upon detecting a connection of a second device that requires a non-revocable current beyond the extra-current budget, wherein the second device is connected to the computer system through a second bus interface, send a first notice to the first device to relinquish the first revocable current; and 
 allocate the non-revocable current to the second device from the extra-current budge, 
   wherein the extra-current budget corresponds to current available from the computer system exceeding current reserved for the bus interfaces of the computer system.   
     
     
         9 . The system of  claim 8 ,
 wherein the management apparatus is further configured to send a second notice to the first device for renegotiation of revocable current, and   wherein the communication apparatus is further configured to generate, for the first device, a second request for a second revocable current.   
     
     
         10 . The system of  claim 9 , wherein the management apparatus is further configured to:
 allocate the second revocable current to the first device from the extra-current budget.   
     
     
         11 . The system of  claim 8 , wherein the management apparatus is further configured to:
 upon detecting a connection of a third device that requires a third revocable current beyond the extra-current budget, wherein the third device is connected to the computer system through a third bus interface and the third device has a higher priority than the first device, send a third notice to the first device to relinquish the first revocable current; and   allocate the third revocable current to the third device from the extra-current budget.   
     
     
         12 . The system of  claim 11 , wherein the management apparatus is further configured to:
 send a second notice to the first device for renegotiation of the revocable current.   
     
     
         13 . The system of  claim 12 ,
 wherein the communication apparatus is further configured to generate, for the first device, a second request for a second revocable current, and   wherein the management apparatus is further configured to allocate the second revocable current to the first device from the extra-current budget.   
     
     
         14 . The system of  claim 8 , wherein the extra-current budget is based on at least one of:
 a number of the bus interfaces;   the current reserved for the bus interfaces; and   a power-management mode associated with the computer system.   
     
     
         15 . A non-transitory computer readable storage medium storing instructions that, when executed by a computer system, cause the computer system to:
 obtain a first request from a first device for a first revocable current beyond a reserved current for a first bus interface, wherein the first device is connected to the computer system through the first bus interface;   allocate the first revocable current based on the first request to the first device from an extra-current budget;   upon detecting a connection of a second device that requires a non-revocable current beyond the extra-current budget, wherein the second device is connected to the computer system through a second bus interface, send a first notice to the first device to relinquish the first revocable current; and   allocate the non-revocable current to the second device from the extra-current budget,   wherein the extra-current budget corresponds to current available from the computer system exceeding current reserved for the bus interfaces of the computer system.   
     
     
         16 . The non-transitory computer readable storage medium of  claim 15 , further comprising instructions to cause the computer system to:
 send a second notice to the first device for renegotiation of revocable current; and   receive a second request from the first device for a second revocable current.   
     
     
         17 . The non-transitory computer readable storage medium of  claim 16 , further comprising instructions to cause the computer system to:
 allocate the second revocable current to the first device from the extra-current budget.   
     
     
         18 . The non-transitory computer readable storage medium of  claim 15 , further comprising instructions to cause the computer system to:
 upon detecting a connection of a third device that requires a third revocable current beyond the extra-current budget, wherein the third device is connected to the computer system through a third bus interface and the third device has a higher priority than the first device, send a third notice to the first device to relinquish the first revocable current; and   allocate the third revocable current to the third device from the extra-current budget.   
     
     
         19 . The non-transitory computer readable storage medium of  claim 15 , further comprising instructions to cause the computer system to:
 send a second notice to the first device for renegotiation of the revocable current;   receive a second request from the first device for a second revocable current; and   allocate the second revocable current to the first device from the extra-current budget.   
     
     
         20 . The non-transitory computer readable storage medium of  claim 15 ,
 wherein the first revocable current varies responsive to use of the first device, and   wherein the non-revocable current varies responsive to use of the second device.