1. A computer system for relinquishing, by a selected processor, the selected processor's own exclusive ownership of a specified cache line, the computer system comprising: a shared cache system; and the selected processor being a processor of a multi-processor system, each processor of the multi-processor system communicatively coupled to said shared cache system, the computer system configured to perform a method comprising: executing, by the selected processor, a demote instruction of a software program, the demote instruction specifying an address of a specified cache line, the executing the demote instruction by the selected processor comprising: based on the computer system determining that the specified cache line in the shared cache system is exclusively owned by the selected processor, causing, by the selected processor, the selected processor's exclusive ownership of the cache line to be relinquished.