linux-kernel - RE: Slowness forming TIPC cluster with explicit node addresses

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Date:   Sun, 4 Aug 2019 21:53:52 +0000
From:   Jon Maloy <jon.maloy@...csson.com>
To:     Chris Packham <Chris.Packham@...iedtelesis.co.nz>,
        "tipc-discussion@...ts.sourceforge.net" 
        <tipc-discussion@...ts.sourceforge.net>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: Slowness forming TIPC cluster with explicit node addresses



> -----Original Message-----
> From: netdev-owner@...r.kernel.org <netdev-owner@...r.kernel.org> On
> Behalf Of Chris Packham
> Sent: 2-Aug-19 01:11
> To: Jon Maloy <jon.maloy@...csson.com>; tipc-
> discussion@...ts.sourceforge.net
> Cc: netdev@...r.kernel.org; linux-kernel@...r.kernel.org
> Subject: Re: Slowness forming TIPC cluster with explicit node addresses
> 
> On Mon, 2019-07-29 at 09:04 +1200, Chris Packham wrote:
> > On Fri, 2019-07-26 at 13:31 +0000, Jon Maloy wrote:
> > >
> > >
> > > >
> > > >
> > > > -----Original Message-----
> > > > From: netdev-owner@...r.kernel.org <netdev-
> owner@...r.kernel.org>
> > > > On Behalf Of Chris Packham
> > > > Sent: 25-Jul-19 19:37
> > > > To: tipc-discussion@...ts.sourceforge.net
> > > > Cc: netdev@...r.kernel.org; linux-kernel@...r.kernel.org
> > > > Subject: Slowness forming TIPC cluster with explicit node
> > > > addresses
> > > >
> > > > Hi,
> > > >
> > > > I'm having problems forming a TIPC cluster between 2 nodes.
> > > >
> > > > This is the basic steps I'm going through on each node.
> > > >
> > > > modprobe tipc
> > > > ip link set eth2 up
> > > > tipc node set addr 1.1.5 # or 1.1.6 tipc bearer enable media eth
> > > > dev eth0
> > > eth2, I assume...
> > >
> > Yes sorry I keep switching between between Ethernet ports for testing
> > so I hand edited the email.
> >
> > >
> > > >
> > > >
> > > >
> > > > Then to confirm if the cluster is formed I use tipc link list
> > > >
> > > > [root@...e-5 ~]# tipc link list
> > > > broadcast-link: up
> > > > ...
> > > >
> > > > Looking at tcpdump the two nodes are sending packets
> > > >
> > > > 22:30:05.782320 TIPC v2.0 1.1.5 > 0.0.0, headerlength 60 bytes,
> > > > MessageSize
> > > > 76 bytes, Neighbor Detection Protocol internal, messageType Link
> > > > request
> > > > 22:30:05.863555 TIPC v2.0 1.1.6 > 0.0.0, headerlength 60 bytes,
> > > > MessageSize
> > > > 76 bytes, Neighbor Detection Protocol internal, messageType Link
> > > > request
> > > >
> > > > Eventually (after a few minutes) the link does come up
> > > >
> > > > [root@...e-6 ~]# tipc link list
> > > > broadcast-link: up
> > > > 1001006:eth2-1001005:eth2: up
> > > >
> > > > [root@...e-5 ~]# tipc link list
> > > > broadcast-link: up
> > > > 1001005:eth2-1001006:eth2: up
> > > >
> > > > When I remove the "tipc node set addr" things seem to kick into
> > > > life straight away
> > > >
> > > > [root@...e-5 ~]# tipc link list
> > > > broadcast-link: up
> > > > 0050b61bd2aa:eth2-0050b61e6dfa:eth2: up
> > > >
> > > > So there appears to be some difference in behaviour between having
> > > > an explicit node address and using the default. Unfortunately our
> > > > application relies on setting the node addresses.
> > > I do this many times a day, without any problems. If there would be
> > > any time difference, I would expect the 'auto configurable' version
> > > to be slower, because it involves a DAD step.
> > > Are you sure you don't have any other nodes running in your system?
> > >
> > > ///jon
> > >
> > Nope the two nodes are connected back to back. Does the number of
> > Ethernet interfaces make a difference? As you can see I've got 3 on
> > each node. One is completely disconnected, one is for booting over
> > TFTP
> >  (only used by U-boot) and the other is the USB Ethernet I'm using for
> > testing.
> >
> 
> So I can still reproduce this on nodes that only have one network interface and
> are the only things connected.
> 
> I did find one thing that helps
> 
> diff --git a/net/tipc/discover.c b/net/tipc/discover.c index
> c138d68e8a69..49921dad404a 100644
> --- a/net/tipc/discover.c
> +++ b/net/tipc/discover.c
> @@ -358,10 +358,10 @@ int tipc_disc_create(struct net *net, struct
> tipc_bearer *b,
>         tipc_disc_init_msg(net, d->skb, DSC_REQ_MSG, b);
> 
>         /* Do we need an address trial period first ? */
> -       if (!tipc_own_addr(net)) {
> +//     if (!tipc_own_addr(net)) {
>                 tn->addr_trial_end = jiffies + msecs_to_jiffies(1000);
>                 msg_set_type(buf_msg(d->skb), DSC_TRIAL_MSG);
> -       }
> +//     }
>         memcpy(&d->dest, dest, sizeof(*dest));
>         d->net = net;
>         d->bearer_id = b->identity;
> 
> I think because with pre-configured addresses the duplicate address detection
> is skipped the shorter init phase is skipped. Would is make sense to
> unconditionally do the trial step? Or is there some better way to get things to
> transition with pre-assigned addresses.

I am on vacation until the end of next-week, so I can't give you any good analysis right now.
To do the trial step doesn’t make much sense to me, -it would only delay the setup unnecessarily (but with only 1 second).
Can you check the initial value of addr_trial_end when there a pre-configured address?

///jon