netdev - Re: What's the right way to use a *large* number of source addresses?

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Message-ID: <1400854458.5367.200.camel@edumazet-glaptop2.roam.corp.google.com>
Date:	Fri, 23 May 2014 07:14:18 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	sowmini varadhan <sowmini05@...il.com>
Cc:	Niels Möller <nisse@...thpole.se>,
	netdev <netdev@...r.kernel.org>, Jonas Bonn <jonas@...thpole.se>
Subject: Re: What's the right way to use a *large* number of source
 addresses?

On Fri, 2014-05-23 at 08:53 -0400, sowmini varadhan wrote:

> I think the issue here is the netlink API: if you try to do the same thing
> with ifconfig (instead of /sbin/ip), you'll find things are much faster,
> which seems paradoxical because ip(7) and netlink sockets are the
> recommended config paths. When I ran into this, it turned out that the
> difference was due to the implementation- the ioctl path was able to
> use the ifr_name efficiently to identify the target interface, unlike
> the netlink config path.

Only if you launch on "ip" command for one IP address it might be slow.

ip populates a cache at startup.

Use the batch mode, and it will be much faster than ifconfig, as
ifconfig does not support this mode (you need one fork()/exec() per IP
address)

ip -batch filename



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