Hello Peter!
> 2 diff things. semap are sync mechanism used - to sync among
> CPUs/processes/tasks etc. Just a counting mechanism. It DOES NOT
> lock the other CPU while another CPU is using the same resources. but
> this counting must be atomic....different arch has different instruction
> set to do it.
I thought that because there is an 'init_MUTEX(struct semaphore *)'
macro, there would be no difference between semaphores and mutex_locks.
So, did I understand it right:
semaphores are only local (for one CPU)?
mutex_locks also lock the other CPUs?
all these API can affect other CPU's behavior.
What do you meen by "all these API"?
I thought the semaphores only affect the behavior of the local CPU...
mutex does not "lock" in the sense of blocking the CPU - but in the
sense that if the lock is not free, the task will be switch out and
another task switch in, done by scheduler.
O.K. I understand so I ask in another way:
For example my work handler is running on CPU0 and holds the mutex_lock.
Then (on CPU1) my work handler also calls mutex_lock.
Will it "see" that the lock is held by the work handler on CPU0 and will
it be switched out by the scheduler?
Regards and Thanks!
Lukas
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