Re: PROBLEM: serial port FIONREAD from realtime thread

[Paul Fulghum <paulkf@microgate.com>]

Dick Hollenbeck wrote:
> 1) Can you point me at the source file(s) where I can explore this 
> further? (source file the workqueue written to).

drivers/char/tty_io.c has the flip buffer code

The function tty_flip_buffer_push() is called by
the hardware driver when data has been added to
the flip buffer. This function calls flush_to_ldisc()
either directly (if low_latency is set) or indirectly
through the workqueue.

There is a problem in setting low_latency if
tty_flip_buffer_push() is called in interrupt context,
which many drivers do. You can try setting this and
seeing if your machine crashes and burns.

This code is a moving target at this time.
Alan Cox is working on bringing
a small measure of sanity to the code.

> 2) How do I determine the priority of the events kernel thread (where is 
> it created, and/or priority set).

You should be able to look at the output of
'top' or 'ps' for the 'events/0' entry.

My machine shows a priority of 10.

-- 
Paul Fulghum
Microgate Systems, Ltd.