Re: [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to refcount_t

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:

quoted

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?

I guess someone could code a lib/test_refcount.c launching X threads
using either atomic_inc or refcount_inc() in a loop.

That would give a rough estimate of the refcount_t overhead among
various platforms.

Its also a fairly meaningless number. It doesn't include any of the
other work the network path does.