Method and apparatus for providing bus arbitrations in a data processing system
View Patent ↗A method and apparatus for providing bus arbitrations in a multiprocessor system is disclosed. A computer system includes a common bus that is shared by multiple cores, such as processors. A history of bus requests for the common bus made by the cores is stored in a bus request history table. In response to bus request made by the cores, the common bus is arbitrated according to information stored in the bus request history table by an arbiter.
1. An apparatus for providing bus arbitrations in a multiprocessor system, said apparatus comprising:
a bus request history table for storing a history of bus requests for a system bus made by a plurality of cores, wherein said bus request history table includes a current sequence number column, a processor sequence column, a next sequence number column, and a number of misses column, wherein said system bus is shared by said plurality of cores; and
an arbiter, coupled to said bus request history table, for arbitrating said system bus among said plurality of cores in response to bus requests made by said plurality of cores, according to information stored in said bus request history table.
2. The apparatus of claim 1 , wherein said bus request history table includes a current bus owner column, a next bus owner column, and a number of misses column.
3. The apparatus of claim 1 , wherein said arbiter, in response to bus requests from a sequence of cores having an entry in said processor sequence column, automatically grants said system bus to a sequence of cores according to a corresponding entry in said next sequence number column after said bus requests.
4. The apparatus of claim 1 , wherein said bus request history table is implemented by content-addressable memory.
5. The apparatus of claim 1 , wherein said core is a processor.
6. The apparatus of claim 2 , wherein said arbiter, in response to a bus request from a core having an entry in said current bus owner column, automatically grants said system bus to a core according to a corresponding entry in said next bus owner column after said bus request.
7. The apparatus of claim 2 , wherein said bus request history table is implemented by a cache memory.
8. A method for providing bus arbitration in a multiprocessor system, said method comprising:
storing a history of bus requests for a system bus made by a plurality of cores in a bus request history table, wherein said bus request history table includes a current sequence number column, a processor sequence column, a next sequence number column, and a number of misses column, wherein said system bus is shared by said plurality of cores; and
in response to bus requests made by said plurality of cores, arbitrating said bus requests according to information stored in said bus request history table.
9. The method of claim 8 , wherein said bus request history table includes a current bus owner column, a next bus owner column, and a number of misses column.
10. The method of claim 8 , wherein said arbitrating further includes automatically grants said system bus to a sequence of cares according to a corresponding entry in said next sequence number column after said bus requests, in response to bus requests from a sequence of cores having an entry in said processor sequence column.
11. The method of claim 8 , wherein said core is a processor.
12. The method of claim 9 , wherein said arbitrating further includes automatically grants said system bus to a core according to a corresponding entry in said next bus owner column after said bus request, in response to a bus request from a core having an entry in said current bus owner column.
13. The method of claim 9 , wherein said bus request history table is implemented by a cache memory.
14. The method of claim 10 , wherein said bus request history table is implemented by content-addressable memory.