What does "REALTIME"/"Realtime Interfaces" mean in the man pages?

[cjappl]

Hi all,

I was wondering if you knew what "REALTIME" meant when it was included in various BSD man pages.

For example:

```
> man 2 aio_return | head
AIO_RETURN(2) System Calls Manual AIO_RETURN(2)

NAME
aio_return – retrieve return status of asynchronous I/O operation
(REALTIME)
> man 2 sigaction | grep -i realtime -A 4
Realtime Interfaces:

aio_error(), sigpause(), aio_return(), aio_suspend(), sem_post(),
sigset().
> apropos realtime | head
aio_cancel(2) - cancel an outstanding asynchronous I/O operation (REALTIME)
aio_error(2) - retrieve error status of asynchronous I/O operation (REALTIME)
aio_read(2) - asynchronous read from a file (REALTIME)
aio_return(2) - retrieve return status of asynchronous I/O operation (REALTIME)
aio_suspend(2) - suspend until asynchronous I/O operations or timeout complete (REALTIME)
aio_write(2) - asynchronous write to a file (REALTIME)
```

These can be found online at places like:

aio_return(2) - Manual pages

sigaction

man.freebsd.org

And seem to be shared across the BSD variants.

In audio code (where I come from), system calls a typically disallowed as they have non-deterministic execution times. I have not seemed to find any info to say definitively what "REALTIME" means on these man pages.

Thanks

 

[oOiOo]

I suppose it is relative to POSIX Realtime extensions
My 2 cents

 

[Deleted member 81054]

In audio code (where I come from), system calls a typically disallowed as they have non-deterministic execution times.

That's only the case for calls/traps that don't address timeliness in their design. You can offer RT extensions to a non-RT OS for special purposes where such guarantees are important. (and, of course, as always, real-time doesn't always mean real FAST!)