Re: 2.4 virtual terminal timing

From: Alan Cox
Date: Wed Nov 10 2004 - 14:44:55 EST

On Mer, 2004-11-10 at 12:58, Tom Schouten wrote:
> i am trying to find out if there is a direct path in 2.4.x from
> keyboard interrupt, through console/tty stuff to process wakeup,
> for a 2 thread process with one thread blocking on tty read,
> running SCHED_FIFO, or a single thread process with async IO.

You hit the keyboard. A microcontroller with a brain the size of a pea
sits around for a bit works out what you hit and we get an interrupt.
that it sends it slowly over a serial link to the PC.

The tty driver figures out the characters and sends them down to the
line discipline layer. The line discipline will wake the user process
from that event.

At least in 2.6 the tty driver isn't doing batching for keyboard
commands that I can see so it ought to be reasonably quick.

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