Aufgabe 4: Kontextwechsel

By the use of Spinlocks, it is possible to serialize blocks of code that might run parallel on multiple CPU cores. More...

#include <sync/spinlock.h>

Public Member Functions
	Spinlock ()
	Constructor; Initializes as unlocked.

void	lock ()
	Enters the critical area. In case the area is already locked, lock() will actively wait for the area can be entered.

void	unlock ()
	Unblocks the critical area.

Detailed Description

By the use of Spinlocks, it is possible to serialize blocks of code that might run parallel on multiple CPU cores.

Synchronization is implemented using a lock variable. Once a thread enters the critical area, it sets the lock variable (to a non-zero value); when this thread leaves the critical area, it resets the lock variable to zero. When trying to enter an already locked critical area, the trying thread actively waits until the critical area is free again.

Use the following two GCC intrinsics

bool __atomic_test_and_set(void *ptr, int memorder)
void __atomic_clear (bool *ptr, int memorder)

These intrinsics are translated into atomic, architecture-specific CPU instructions.

Note: If you want that things just work, choose __ATOMIC_SEQ_CST as memorder. This is not the most efficient memory order but works reasonably well.

Atomic Builtins in GCC manual

The documentation for this class was generated from the following file:

sync/spinlock.h

Public Member Functions

Detailed Description