Re: 2.0.6 Networking strangeness
Linus Torvalds (torvalds@cs.helsinki.fi)
Tue, 16 Jul 1996 09:58:57 +0300 (EET DST)
On Mon, 15 Jul 1996 tytso@MIT.EDU wrote:
>
> Date: Sun, 14 Jul 1996 13:37:22 +0300 (EET DST)
> From: Linus Torvalds <torvalds@cs.helsinki.fi>
>
> However, this behaviour makes me suspect more and more that there is
> something broken in the PPP (or serial code) timings,
>
> Well, there is a known problem in the tty layer, which is that upper
> layer processing doesn't happen except on the next clock tick. Hence,
> there is on average a .005 second delay between when the PPP framing
> character comes in and when it actually gets processed.
I know about this, and I consider it reasonable - it does mean that
latency for serial lines are about 10ms regardless of the speed of the
line, but I don't _really_ consider this a problem (the only place it
shows up is "ping", because TCP should be able to handle it with the
windows anyway for any reasonable speed for the serial line).
We might want to fix it some day, but that one shouldn't have been the
cause of this (when the delays were on the order of hundreds of ms,
rather than 10ms). And as it turns out, it seems the problem was a false
alarm anyway.
Linus