Subject: Re: scp stalls mysteriously

From: Frederic Leroy <[email-masked]>
Date: Mon, 30 Nov 2009 19:50:04 +0100

Le Sat, 28 Nov 2009 13:31:14 +0200 (EET),
"Ilpo Järvinen" <[email-masked]> a écrit :

> I restored Ccs. Please keep them.

Sorry, 

> On Sat, 28 Nov 2009, Frederic Leroy wrote:
> 
> > Le Sat, 28 Nov 2009 00:12:23 +0200 (EET),
> > "Ilpo Järvinen" <[email-masked]> a écrit :
> > 
> > > On Fri, 27 Nov 2009, Frederic Leroy wrote:
> > > 
> > > > I put traces of stall here : 
> > > > http://www.starox.org/pub/scp_stall/
> [...]
> Perhaps having the /proc/net/tcp would at least tell what state the
> timer is (if I cannot reproduce right away). ...It is rather strange
> that two independent mechanisms for loss recovery seem both to fail
> to get triggered here, no traces of retransmission whatsoever. I
> think it is for now enough to concentrate on what happens on
> 192.168.1.15 (=houba?) and get tcpdump and proc/net/tcp from there,
> the other end/direction has very little significance here (except for
> the fact that bidirectionality might be needed to actually trigger
> it). You could even think of getting proc/net/tcp a bit more often,
> right from the start:
> 
> while [ : ]; do grep ":0016" /proc/net/tcp; sleep 0.1; done | tee
> scp_stall-houba.x.proc_net_tcp
> 
> ...Please wait at least 2 minutes before hitting ctrl-c or otherwise 
> artificially intervening.

You're right, 192.168.1.15 is houba.
The faulty behaviour comes back today, I did new captures on
192.168.1.15 only : 
http://www.starox.org/pub/scp_stall/scp_stall-houba.2.pcap
http://www.starox.org/pub/scp_stall/scp_stall-houba.2.proc_net_tcp
http://www.starox.org/pub/scp_stall/scp_stall-houba.3.pcap
http://www.starox.org/pub/scp_stall/scp_stall-houba.3.proc_net_tcp

Which tool do you use to analyze /proc/net/tcp ?

-- 
Frédéric Leroy