Re: Testing interface removal speedup patches from Eric Dumazet.

--On 9 May 2011 12:02:47 -0700 Ben Greear [off-list ref] wrote:

quoted

So Eric's patches help in the interface create case, even though
there is no synchronize_net, sychronize_sched() or rcu_barrier() there.

I had assumed the slow create (which varies by number of pairs) was
down to sysfs scalability only (see difference between 14ms and 110ms
there).

I'm not certain the create case is actually faster.  Other runs on the
patched kernel showed create to be much closer to the un-patched kernel.

The ratios to create/delete are more consistent it seems.

quoted

Out of interest, if you still happen to have the scripts around, how
fast is veth creation if you just do 100 pairs?

Created 500 veth in 17.874695 seconds (0.03574939 per interface).
Created 100 veth in 2.779905 seconds (0.02779905 per interface).

Hmmm... well you are getting *far* better linearity than me. Creating
500 interfaces is 8 times slower *per interface* than doing 500.

What occurs to me is that your box is faster than one of the ones I tested
on, and you use CONFIG_HZ=100 but you get poorer results in absolute terms
doing 100 (I see 14ms per interface). This with everything listenting to
udev disabled? (so udevd dead, whatever executes your ifup/down scripts
dead, unshare -n).

-- 
Alex Bligh