On Wed, 2017-03-22 at 16:08 +0100, Peter Zijlstra wrote: > On Wed, Mar 22, 2017 at 07:54:04AM -0700, Eric Dumazet wrote: > > On Wed, 2017-03-22 at 15:33 +0100, Peter Zijlstra wrote: > > > > > > > > But I would feel a whole lot better about the entire thing if we could > > > measure their impact. It would also give us good precedent to whack > > > other potential users of _nocheck over the head with -- show numbers. > > > > I wont be able to measure the impact on real workloads, our productions > > kernels are based on 4.3 at this moment. > > Is there really no micro bench that exercises the relevant network > paths? Do you really fully rely on Google production workloads? You could run a synflood test, with ~10 Mpps. sock_hold() is definitely used in SYN handling. Last upstream kernels do not work on my lab hosts, for whatever reason.