Timed memory access
Shared memory access in a distributed system, including: determining, in response to a memory access request, based on a time value, an entry in an access permissions table by: determining, based on a modulo of the time value and a number of entries in the access permissions table, a table index; determining, based on the table index, the entry; and determining, based on the entry, whether to allow the memory access request.
1. A method for shared memory access in a distributed system, comprising:
determining, in response to a memory access request, based on a time value, an entry in an access permissions table by:
determining, based on a modulo of the time value and a number of entries in the access permissions table, a table index;
determining, based on the table index, the entry; and
determining, based on the entry, whether to allow the memory access request.
2. The method of claim 1 , further comprising:
loading, into a remote data memory access engine, the access permissions table; and
receiving, by the remote data memory access engine, the memory access request.
3. The method of claim 1 , wherein the access permissions table is implemented in a memory management unit (MMU).
4. The method of claim 3 , wherein determining whether to allow the memory access request is further based on a virtual address and/or an address space identifier in the entry.
5. The method of claim 1 , wherein the memory access table comprises a plurality of entries indicating, for each node of a plurality of nodes, one or more memory access permissions.
6. The method of claim 5 , wherein the plurality of nodes comprise a plurality of nodes of a distributed automation computing system of an autonomous vehicle.
7. The method of claim 5 , wherein the time value is based on a clock signal synchronized between the plurality of nodes.
8. An apparatus for shared memory access in a distributed system, the apparatus configured to perform steps comprising:
determining, in response to a memory access request, based on a time value, an entry in an access permissions table by:
determining, based on a modulo of the time value and a number of entries in the access permissions table, a table index;
determining, based on the table index, the entry; and
determining, based on the entry, whether to allow the memory access request.
9. The apparatus of claim 8 , wherein the steps further comprise:
loading, into a remote data memory access engine, the access permissions table; and
receiving, by the remote data memory access engine, the memory access request.
10. The apparatus of claim 8 , wherein the access permissions table is implemented in a memory management unit (MMU).
11. The apparatus of claim 10 , wherein determining whether to allow the memory access request is further based on a virtual address and/or an address space identifier in the entry.
12. The apparatus of claim 8 , wherein the memory access table comprises a plurality of entries indicating, for each node of a plurality of nodes, one or more memory access permissions.
13. The apparatus of claim 12 , wherein the plurality of nodes comprise a plurality of nodes of a distributed automation computing system of an autonomous vehicle.
14. The apparatus of claim 12 , wherein the time value is based on a clock signal synchronized between the plurality of nodes.
15. A computer program product disposed upon a non-transitory computer readable medium, the computer program product comprising computer program instructions for shared memory access in a distributed system that, when executed, cause a computer to carry out steps comprising:
determining, in response to a memory access request, based on a time value, an entry in an access permissions table by:
determining, based on a modulo of the time value and a number of entries in the access permissions table, a table index;
determining, based on the table index, the entry; and
determining, based on the entry, whether to allow the memory access request.
16. The computer program product of claim 15 , further comprising:
loading, into a remote data memory access engine, the access permissions table; and
receiving, by the remote data memory access engine, the memory access request.
17. The computer program product of claim 15 , wherein the access permissions table is implemented in a memory management unit (MMU).
18. The computer program product of claim 17 , wherein determining whether to allow the memory access request is further based on a virtual address and/or an address space identifier in the entry.
19. The computer program product of claim 15 , wherein the memory access table comprises a plurality of entries indicating, for each node of a plurality of nodes, one or more memory access permissions.
20. The computer program product of claim 19 , wherein the plurality of nodes comprise a plurality of nodes of a distributed automation computing system of an autonomous vehicle.