Re: txqueuelen has wrong units; should be time

From: Eric Dumazet
Date: Sun Feb 27 2011 - 02:54:38 EST

Le dimanche 27 fÃvrier 2011 Ã 08:02 +0100, Mikael Abrahamsson a Ãcrit :
> On Sun, 27 Feb 2011, Albert Cahalan wrote:
> > Nanoseconds seems fine; it's unlikely you'd ever want
> > more than 4.2 seconds (32-bit unsigned) of queue.
> I think this is shortsighted and I'm sure someone will come up with a case
> where 4.2 seconds isn't enough. Let's not build in those kinds of
> limitations from start.
> Why not make it 64bit and go to picoseconds from start?
> If you need to make it 32bit unsigned, I'd suggest to start from
> microseconds instead. It's less likely someone would want less than a
> microsecond of queue, than someone wanting more than 4.2 seconds of queue.

32 or 64 bits doesnt matter a lot. At Qdisc stage we have up to 40 bytes
available in skb->sb[] for our usage.

Problem is some machines have slow High Resolution timing services.

_If_ we have a time limit, it will probably use the low resolution (aka
jiffies), unless high resolution services are cheap.

I was thinking not having an absolute hard limit, but an EWMA based one.

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