Re: [RFC/T][PATCH 2/3] rc80211-pid: introduce PID sharpening factor

[Mattias Nissler <mattias.nissler@gmx.de>]

On Mon, 2007-12-10 at 00:31 +0100, Stefano Brivio wrote:
> On Sun, 09 Dec 2007 23:29:21 +0100
> Mattias Nissler <mattias.nissler@gmx.de> wrote:
> 
> > Note that current rate_control_pid_sample() is only called from
> > rate_control_pid_tx_status(), which does an tx_num_xmit++ in advance. So
> > the tx_num_xmit branch should actually never be executed (I kept it only
> > to guard against any division by zero errors).
> 
> Eek? Removing the misleading comment would have been nice...

Indeed. I'll amend it :-)

> where does
> interpolation occur now? I got a bit confused by this.

There is no interpolation so far :-) Rate control isn't called
periodically, but only when tx status reports come in. Therefore,
currently we have fixed interval sampling only when packets are sent at
a high enough rate, i.e. 1 packet per second. I'd like to keep it that
way, so we save the timer and don't have to worry about synchronization.
I guess you rather want to base your sharpening patch on the jiffies -
last_sample difference. If it's to much, there haven't been many packets
recently. This will also work when rate control is started, cause
last_sample == 0 then.

Mattias