[openib-general] Re: [PATCH] TX/RX_RING_SIZE as loadable parameters

[Talpey, Thomas]

At 06:21 PM 3/7/2006, Roland Dreier wrote:
>I did a little bit of testing a while ago, and I had a hard time ever
>getting the TX ring to fill up with the current default size.

The ring might fill in other cases, e.g. on a 1x port, if the network is
busy, or flaky. Of course in those cases, packet loss may be a fact
of life. Still, the tx ring number is generally related to the link speed
and send-interrupt strategy.

>    Thomas> Constants are pretty much never correct in networking
>    Thomas> code. And module parameters are darn close to being
>    Thomas> constants.
>
>But if we provide a million little knobs, no one can ever tune
>things.  For example what's the advantage of having a small TX ring?
>Maybe we should just make it big by default.

I did *not* advocate knobs. I hate knobs too. I prefer adaptive
algorithms in code that is designed to deal with differing real-world
network situations. But those are hard, and should be implemented
thoughtfully.

Tom.