Subject: Re: [RFC][PATCH] iproute: Faster ip link add, set and delete

From: Serge Hallyn <[email-masked]>
Date: Wed, 27 Mar 2013 23:28:08 -0500

Quoting Eric W. Biederman ([email-masked]):
> Serge Hallyn <[email-masked]> writes:
> 
> > Quoting Eric W. Biederman ([email-masked]):
> >> Stephen Hemminger <[email-masked]> writes:
> >> 
> >> > If you need to do lots of operations the --batch mode will be significantly faster.
> >> > One command start and one link map.
> >> 
> >> The problem in this case as I understand it is lots of independent
> >> operations. Now maybe lxc should not shell out to ip and perform the
> >> work itself.
> >
> > fwiw lxc uses netlink to create new veths, and picks random names with
> > mktemp() ahead of time.
> 
> I am puzzled where does the slownes in iproute2 come into play?

Benoit originally reported slowness when starting >1500 containers.  I
asked him to run a few manual tests to figure out what was taking the
time.  Manually creating a large # of veths was an obvious test, and
one which showed poorly scaling performance.

May well be there are other things slowing down lxc of course.

-serge