[linux-dvb] Re: [PATCH] Skystar2 pid filters reorganization

[Roberto Ragusa <r.ragusa@libero.it>]

On Thu, 27 Nov 2003 09:57:13 +0100
Niklas Peinecke <peinecke@gdv.uni-hannover.de> wrote:

> Your changes give a rather 
> small improvement in readability but reduce the execution speed further 
> (more arguments passed -> less speed).

I think that having copy&pasted functions is awful. I'm happy to see that
the extra filters are handled through a single function (+id parameter),
that is the same thing I did :-)
You used "case:" for 0/1/2/3/4/5 and "default:" for the others, maybe we
should have two "case:" pointing to two functions or just a single one,
pushing the decision down to add_hw_pid and remove_hw_pid (a filter is
a filter, the hw functions should do the dirty work themselves).

Maybe we can avoid the extra structures I introduced and do something
cleaner (#define? calculations?).

As regards execution speed, we're talking about adding/removing pids, so
something called a very small number of times. You should also consider
code size; smaller coder is always welcome in kernel space (for speed
reasons too), isn't it?
We should really do something smarter in check_pid (interrupt handling)
because having 0x27 "if" is slow, we should limit the search to the
active filters only.

I see that you are planning a better usage of openbandwith, having
a closebandwith too.

Do you want to avoid the "software filtering" completely?
It could be useful to go beyond 0x27 (it is not a small number,
but removing limits is always good).

I'm sure these discussions will bring us a better skystar2.c in a few
days.

BTW, does scan work reliably for you?

-- 
   Roberto Ragusa    r.ragusa at libero.it


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