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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Mon, 20 Mar 2017 14:40:17 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Herbert Xu <herbert@...dor.apana.org.au>
Cc:     David Miller <davem@...emloft.net>, eric.dumazet@...il.com,
        elena.reshetova@...el.com, keescook@...omium.org,
        netdev@...r.kernel.org, bridge@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org, kuznet@....inr.ac.ru,
        jmorris@...ei.org, kaber@...sh.net, stephen@...workplumber.org,
        ishkamiel@...il.com, dwindsor@...il.com, akpm@...ux-foundation.org
Subject: 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:
> >
> > 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.