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Mutex and vTaskSuspendAll

Posted by Sergio Prado on July 30, 2012
Hello all,

I was wondering what is the difference between using a mutex and a vTaskSuspendAll() call.

Why would I disable the scheduler to access a shared resource since I can use a mutex instead?

Thanks in advance,

Sergio Prado

RE: Mutex and vTaskSuspendAll

Posted by Richard Walters on July 31, 2012
vTaskSuspendAll stops the scheduler from switching tasks, whereas a mutex just suspends the tasks waiting for it until the mutex is available. In most cases, a mutex is preferable since it only blocks the few tasks that actually want the mutex, and doesn't prevent non-interested tasks from running. You only want to ever use vTaskSuspendAll in those rare cases where you absolutely need the current task to continue running without being preempted by other tasks. Generally in a well-designed system these cases are all going to be inside the kernel -- in FreeRTOS code itself.

RE: Mutex and vTaskSuspendAll

Posted by Sergio Prado on July 31, 2012
Perfect Richard, thanks!

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