What happens if two processors try to access the global memory at the exact same instant?

What happens if two CPU s in a multiprocessor attempt to access exactly the same word of memory at exactly the same instant? It completes its memory operation, then the other one happens.

Can one process run on multiple cores?

2 Answers. Yes, a single process can run multiple threads on different cores. Caching is specific to the hardware. Many modern Intel processors have three layers of caching, where the last level cache is shared across cores.

What are the operations performed within the test-and-set instruction?

In computer science, the test-and-set instruction is an instruction used to write (set) 1 to a memory location and return its old value as a single atomic (i.e., non-interruptible) operation. The caller can then “test” the result to see if the state was changed by the call.

Why the Test-and-Set () is called an atomic operation justify your answer?

Test-and-set instruction returns the old value of memory location (lock) and updates its value to 1 simultaneously. The fact that these two operations are performed as a single atomic operation ensures mutual exclusion.

What is the main job of the CPU?

The central processing unit (CPU) guides the computer through the various steps of solving a problem. Data enters the computer through an input unit, is processed by the central processing unit, and is then made available to the user through an output unit.

What is a test-and-set instruction how can it be used to implement mutual exclusion consider using a fragment of psuedo assembly language to aid your explanation?

What is a test-and-set instruction? How can it be used to implement mutual exclusion? Consider using a fragment of psuedo-assembly language aid you explanation. Test and set instruction is an atomic instruction which will test the value of a register and then set it to the value given to the instruction.

Why is a set and test necessary?

Test-and-set helps us fix that problem by checking that the value your overwriting is what you think it should be. In this case, you can check that the balance was the original value that you read. Since it’s atomic, it’s non-interruptible so no-one can pull the rug out from under you between the read and the write.

Which process can be affected by another process executive in the system?

Explanation: A cooperating process can be affected by other processes executing in the system. Explanation: If a process is executing in its critical section, then no other processes can be executed in their critical section. This condition is called Mutual Exclusion.

Which environment do we use test and set?

In computer science, the test-and-set CPU instruction is used to implement mutual exclusion in multiprocessor environments.

How the CPU executes program instructions?

In general, a CPU executes an instruction by fetching it from memory, using its ALU to perform an operation, and then storing the result to memory.

Can multiple processes run simultaneously in a dual core processor?

2 Answers 2. Yes multiple processes can run simultaneously (without context-switching) in multi-core processors. If all processes are single threaded as you ask then 2 processes can run simultaneously in a dual core processor. The same for multi-threaded processes as you ask, 2 processes again, one for each core could run at the same time.

What would happen if two cores tried to access the same RAM?

This is what I guess would happen: If two cores tried to access the same address in RAM, one would have to wait for the other to access the RAM. The second time that each core would try to access the same address, they may still have that RAM cached, so they could access their respective caches simultaneously.

Why can other processes enter only after the test-and-test finishes?

Other processes can enter only after the process that has begin the test-and-test finishes and set the lock value to 0. This prevents the occurrence of deadlock. This synchronization mechanism does not guarantee bounded waiting. This synchronization mechanism may cause a process to starve for the CPU.

How many threads can a single core run?

For a quad core the same occurs with 4 processes and the fifth and so on. Do not confuse multi-core with multi-thread support. 1 core may be able to run just 1 or more threads (if it is single-threaded core or multi-threaded core respectively).