On Tue, 29 May 2007 23:58:39 +0300 (EEST)
"Ilpo Järvinen" <[EMAIL PROTECTED]> wrote:
> On Tue, 29 May 2007, Stephen Hemminger wrote:
>
> > On Tue, 29 May 2007 23:07:00 +0300 (EEST)
> > "Ilpo Järvinen" <[EMAIL PROTECTED]> wrote:
> >
> > > On Tue, 29 May 2007, Stephen Hemminger wrote:
> > >
> > > > Since we don't invoke congestion control modules until after the SYN
> > > > handshake this is not a problem.
> > >
> > > Just curious, do you mean that cc modules cannot measure, e.g., initial
> > > RTT through this mechanism (though they could do that in init() cb then
> > > I suppose)... Or do you mean that they are called already for the ACK
> > > that completes the SYN handshake and therefore its skb is being cleaned
> > > from the queue right now (this is the case I above refer to)?
> > > In the first case the decrementer code is NOP. If the latter, then it
> > > is just interface specification question, i.e., if SYNs are treated as
> > > zero or one in num_acked for the pkts_acked callback (I have no opinion
> > > on this but was just trying to make sure cc modules get what they
> > > expect :-)).
> >
> > We don't switch a socket out of Reno until after the initial handshake.
>
> ...It's still not very clear to me what exactly your "after" means (both
> here and in your earlier description), i.e., whether clean_rtx_queue call
> that cleans SYN skb from the queue happens before or after the switch out
> of reno or not... If I understand the code correctly, this specific
> clean_rtx_queue call happens after "your after" but I could be
> misunderstanding the current 3-way handshake code. :-)
The call to clean_rtx_queue and congestion control routine happens here:
tcp_ack
tcp_clean_rtx_queue
cong->pkts_acked
Setup of congestion control happens here:
tcp_ack
tcp_rcv_syn_sent_state_process
tcp_init_congestion_control
or here:
tcp_ack
tcp_rcv_state_process (case ack of TCP_SYN_RECV)
tcp_init_congestion_control
Another benefit of this, is that when tcp_init_congestion_control is called
things like the srtt and initial sequence number have already been setup.
> > As an interface, it makes sense to keep the API with the SYN counting
> > as a packet.
>
> Ok, this one answers the remaining question concerning the patch, here
> is it without the decrementer for SYN case (which IMHO wasn't very
> beautiful looking anyway :-)).
>
> Dave, please consider this to net-2.6. It could be a stable candidate
> as well, haven't tested yet if it applies cleanly to stable:
--
Stephen Hemminger <[EMAIL PROTECTED]>
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