Subject: Re: Proposed changes to cc_microset().
To: None <>
From: Martin Husemann <>
List: tech-kern
Date: 07/06/2004 09:38:54
On Tue, Jul 06, 2004 at 12:24:44AM -0500, Frederick Bruckman wrote:

> It could say "about 1/10 second" or "about 10 seconds", or it could say
> "short interval" and "long interval", and let the actual numbers be varied
> (by experiment) for each port.

Having those overridable per port sounds good.

> Right. I don't know either. That's definitely the biggest possible
> downside. For what it's worth, it doesn't *feel* any more sluggish.

If the interval is tunable per port (and maybe via a kernel config option)
we can experiment for the slower SMP machines. I have some ;-)

> In order for cc_microset() to utilize a longer interval to calibrate the
> ratio, it needs to know if the 32-bit counter has rolled over, and how
> many times, and the only way to do that, is to track it on the short
> interval.

Maybe we can make this tunable per port too. There are counters with more
than 32bit (which we currently mask to 32bit only) and there are archs that
easily can calculate with 64bit values.