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Re: netlink drops messages.

To: "James R. Leu" <jleu@xxxxxxxxxxxxxx>
Subject: Re: netlink drops messages.
From: Andi Kleen <ak@xxxxxx>
Date: Wed, 17 Jan 2001 17:13:10 +0100
Cc: Andi Kleen <ak@xxxxxx>, Werner Almesberger <Werner.Almesberger@xxxxxxx>, kuznet@xxxxxxxxxxxxx, gleb@xxxxxxxxxxx, netdev@xxxxxxxxxxx
In-reply-to: <20010117074952.C2459@doit.wisc.edu>; from jleu@mindspring.com on Wed, Jan 17, 2001 at 02:51:19PM +0100
References: <20010116124319.D1299@doit.wisc.edu> <200101161848.VAA31729@ms2.inr.ac.ru> <20010116131456.E1299@doit.wisc.edu> <20010117040542.Y18286@almesberger.net> <20010117121532.B1830@fred.local> <20010117074952.C2459@doit.wisc.edu>
Sender: owner-netdev@xxxxxxxxxxx
On Wed, Jan 17, 2001 at 02:51:19PM +0100, James R. Leu wrote:
> Hello, 
> 
> On Wed, Jan 17, 2001 at 12:15:32PM +0100, Andi Kleen wrote:
> > On Wed, Jan 17, 2001 at 04:08:14AM +0100, Werner Almesberger wrote:
> > > James R. Leu wrote:
> > > > I'm not asking for the impossible.  Sequence numbers and/or client
> > > > to server ACKs would solve the problem.
> > > 
> > > So what do you do when the client doesn't ACK and you run out of buffer
> > > space ? Block all activities that may trigger netlink messages ?
> > > 
> > > Obviously, in this case (interface up/down transitions), netlink doesn't
> > > scale well. A state-based interface would be better, e.g. netlink could
> > > generate a bit vector indicating the states (or the transitions, if it
> > > matters whether any have occurred), and update the vector until it has
> > > been read by the client. The question is of course whether we really
> > > need an optimized, scalable solution for this.
> > 
> > A simple way is to delete ip addresses when you down an interface and use
> > regular SIOCGIFCONF. 
> 
> That is basically a dump of the entire inteface table!  If we are talking
> about 16K interfaces that is an awful lot of work just because an interface
> when down or up.


The thread was: when only a few interfaces go up/down then netlink messages
work fine.
Then someone complained that the netlink buffer overflows when too many 
interfaces
go up/down. In this case you can do a whole resynchronization regularly (e.g. 
every 
minute) and do less work overall. 



-Andi

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