Extended atomic operations

Claim 2

A lock-free method for serializing access to a shared resource among concurrent processes in either a multiprogramming pre-emptive scheduling environment or where at least two processors share a common main store, wherein process access to resources includes the indivisible step of reading a resource status variable, storing its value in a save area, and, conditioned on the value of the variable, altering said variable, comprising the steps of: storing each resource status variable in a main store location; and the further indivisible steps of: partially executing against a resource status variable at said main store location by one process while checking for resource contention from another process; and in the event of resource contention between processes, passing an obligation to complete the execution against the resource status variable at said main store location to one of said contending processes.

Claim 3

The method of claim 1 wherein said obligation is passed to the first of said contending processes to partially execute against said resource status variable.

Claim 4

The method of claim 1 wherein said obligation is passed to the last of said contending processes to partially execute against said resource status variable.

Claim 5

The method of claim 1 wherein each resource status variable includes three words, only two of which need be contiguously stored.

Claim 6

The method of claim 1 wherein each resource status variable includes three words, two of which are contiguously stored.

Claim 9

The method of claim 6 wherein said obligation is passed to the first of said two or more processes performing said initiation operation.

Claim 10

The method of claim 6 wherein said obligation is passed to the last of said two or more processes performing said initiation operation.

Claim 11

The method of claim 6 wherein said resource status variable includes three words, only two of which need be contiguously stored.

Claim 12

The method of claim 6 wherein said resource status variable includes at least three words, two of which are contiguously stored.

Claim 13

The method of claim 7 wherein said shared resource includes a communication channel.

Claim 14

The method of claim 8 wherein said shared resource includes a linked data list.

Claim 15

In a processing system including a storage facility, plural concurrently-executing processes, at least one shared resource, and operating system means for managing the use of said shared resource by said processes, the improvement comprising a resource allocation system in said operating system for permitting concurrent, non-exclusive use of said shared resource by said processes, said resource allocation system comprising: an undivided resource status data object stored in said storage facility for indicating use of the shared resource by one or more of said processes; atomic operation means for, each time a process uses said resource, indivisibly reading said resource status data object, storing the value of said resource status data object in a save area of said processing system, and, based upon the value of said resource status data object, altering said variable to indicate said use; and logic means executable by said processes for enabling a process to, by means of said atomic operation means, partially execute against said resource status data object while checking for contention for the resource from another process and for, in the event of resource contention between said partially executing process and another process, passing an obligation to complete execution against said resource status data object to one of said competing processes.

Claim 16

In a processing system including a storage facility, plural concurrently-executing processes, at least one shared resource, and operating system means for managing the use of said shared resource by said processes, the improvement comprising a resource allocation system in said operating system for permitting concurrent, non-exclusive use of said shared resource by said processes, said resource allocation system comprising: an undivided resource status data object stored in said storage facility for indicating use of the shared resource by one or more of said processes; atomic operation means for, each time a process uses said resource, indivisibly reading said resource status data object, storing the value of said resource status data object in a save area of said processing system, and, based upon the value of said resource status data object, altering said variable to indicate said use; and logic means executable by said processes for enabling a process to, by means of said atomic operation means, partially execute against said resource status data object while checking for contention for the resource from another process and for, in the event of resource contention between said partially executing process and another process, passing an obligation to complete execution against said resource status data object to one of said competing processes.

Claim 17

The improvement of claim 13 wherein said obligation is passed to the first of said contending processes to partially execute against said resource status variable.

Claim 18

The improvement of claim 13 wherein said obligation is passed to the last of said contending processes to partially execute against said resource status variable.

Claim 19

The improvement of claim 13 wherein said resource status data object includes three words, only two of which need be contiguously stored.

Claim 20

The improvement of claim 13 wherein said resource status data object includes three words, two of which are contiguously stored.

Claim 21

The improvement of claim 13 wherein said shared resource includes a communication channel.

Claim 22

The improvement of claim 13 wherein said shared resource includes a linked list of data objects.