CODEWITHSUNDEEP
multithreadingconcurrencyoperating-system
user3759177
user3759177

Reputation: 149

Why thread need to disable interrupts to implement lock?

I read everywhere that to implement a lock thread need hardware support - disable interrupts.

No matter how we choose to implement locks, we must have some hardware support. One possibility to implement locks is to disable interrupts,

Upvotes: 1

Views: 521

Answers (1)

user3344003
user3344003

Reputation: 21617

What you are describing was the mechanism used for simple locking in older OSes that operated on single processor systems. Even then, complex locking (e.g., for a database) required a lot more.

Now, with multiprocessor systems, blocking interrupts all the processors at the same time would not help.

CPUs that support multi-processing have memory interlocked instructions.The olde VAX had an interlocked branch on bit set and set instruction and even a remove from queue interlocked instruction for heavy duty work. Such hardware support has been around for a long time.

Upvotes: 1

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