[LARTC] Determing the pfifo backlog

[Ioannis C Avramopoulos (iavramop@Princeton.EDU)]

Greetings --

in the "Linux Advanced Routing & Traffic Control HOWTO"
chapter 14.1 on bfifo/pfifo it says that:
"you can use this qdisc to determine the backlog on your interface".
But it does not say exactly how.

Command [#tc -s qdisc ls] outputs the number of packets sent so far
but it does not output any info about the backlog.

My first question is whether a command exists that provides info
about the backlog.

My second question is whether a system call exists that provides this
info. I would like to be able to query on the backlog at real time
and invoking the shell on each such query sounds like a lot of overhead.

Kind regards,
Yannis