[RFC] batched tc to improve change throughput

[Thomas Graf <tgraf@suug.ch>]

While collecting performance numbers for the ematch changes
I realized that the throughput of changes per second is
almost only limited by the cost of starting the tc binary
over and over. In order to improve this, batching of commands
is required. My plan to do so is quite simple, introduce
a new flag -f which puts tc into batched mode and makes
it read commands from stdin. A bison based parser splits
things into tokens, the grammer would be quite easy:

INPUT ::= { /* empty */ | CMDS }
CMDS  ::= { CMD | CMD ';' CMDS }
CMD   ::= ARGS
ARGS  ::= { STRING | STRING ARGS }

The lexical part can be made to ignore c-syle and
shell-style comments, i.e.

---
#!/sbin/tc -f

/* some comments here */
qdisc add ..
class ...

# shell like comments also possible
filter add ... basic match ...
---

Of course this loses ability to use shell features like
variables and loops and it's probably not worth trying
to emulate things. One can always generate these tc scripts
with the help of other tools like m4, you name it.

This could also be applied to ip of course.

Thoughts?