read() and write() behavior in *NIX

[jorba101]

When the file descriptor on which read() and write() apply is set up in such a way so that these syscalls block (for instance, until no data is available to read() from a serial port), I wonder following:

What's the processor doing with this process while waiting, in general, in a *NIX? Is it busy-waiting, or sleeping?

[JosAH]

It's going to schedule another task/process because your task can't run anymore.

kind regards,

Jos

[jorba101]

Who'll remember my task is waiting for a semaphore? The OS?

[mac11]

Who'll remember my task is waiting for a semaphore? The OS?

I would say so - process scheduling is part of the OS's job description.