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

On Mon, Mar 20, 2017 at 09:27:13PM +0800, Herbert Xu wrote:

On Mon, Mar 20, 2017 at 02:23:57PM +0100, Peter Zijlstra wrote:

quoted

So what bench/setup do you want ran?

You can start by counting how many cycles an atomic op takes
vs. how many cycles this new code takes.

On what uarch?

I think I tested hand coded asm version and it ended up about double the
cycles for a cmpxchg loop vs the direct instruction on an IVB-EX (until
the memory bus saturated, at which point they took the same). Newer
parts will of course have different numbers,

Can't we run some iperf on a 40gbe fiber loop or something? It would be
very useful to have an actual workload we can run.