Re: [PATCH 3/3] Convert the UDP hash lock to RCU

David Miller
2008-10-06T21:40:38Z

From: Eric Dumazet <dada1@cosmosbay.com>
Date: Mon, 06 Oct 2008 23:22:31 +0200

> Me wondering what impact this synchronize_rcu() can have on mono-threaded
> VOIP applications using lot of UDP sockets. What is the maximum delay of
> this function ?

The cost is enormous, we really can't use it here.

I have a patch that did top-level socket destruction using RCU,
and that didn't use synchronize_rcu(), and that killed connection
rates by up to %20.

I can only imagine what the cost would be if I had to add such a call
in there.

Really, I can't consider these changes seriously, as-is.