On 6/7/06, Arjan van de Ven <arjan@xxxxxxxxxxxxx> wrote:
On Tue, 2006-06-06 at 17:27 +0530, Rajat Jain wrote: > Hi, > > I would appreciate if some one could explain the difference between > "completion" variables and the semaphores in Linux. > > As far as I can understand, both are used to provide synchronization > among kernel threads. Both have similar mechanism i.e. one or more > tasks wait on the completion variable (or semaphore) while another > task holds it and does some work (in critical section). When the task > holding the completion variable (or semaphore) is done, it signals the > other task using "complete" (or "up"). This would cause the waiting > tasks to wait up. > > So why have two different things to do the same thing? they don't do the same thing just like a hammer and a couch are two different things. a completion is for doing "wait until this event is finished", while a semaphore (well don't use semaphores, use a mutex nowadays) is for providing mutual exclusion for a piece of data. Totally different things.
Where can I find the refference to completion variables in kernel ..... regards, Gaurav
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