Yes, I am aware that the entire queue is run. My point was that
it can take longer than one jiffy to complete all of the tasks
on the timer task queue. In that case it "misses" running the
task queue for the next clock tick because it is *still* running
the queue for the previous tick. In that case, an entire run
through the timer task queue is not made every clock tick.
>If we rule out disabling because of page faults, my next hypothesis
>would be that PPP processing itself may be taking sufficiently long that
>the timer starts missing ticks. This might make sense considering that
>existing flow control mechanisms are triggered by the n_tty receive
>buffer filling, not by processing time causing missed clock ticks.
Yes, but why not just do flow control directly in the serial driver?
I have been running my serial.c modified to do flow control inside
the receive_chars() interrupt routine and am getting 13.5K/s FTP
rates running non-compressed 128K ISDN. It'll be even faster once
I dump the diagnostic code and tune it.
>I'll take a look at the PPP code; it may be that we need a way to invoke
>flow control based on time rather than buffer space considerations.
I don't think it is necessary.
-Rob