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

From	Peter Zijlstra <peterz@infradead.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to refcount_t
Date	2017-03-22 14:50 +0100
Message-ID	<tnOOd-3b8-15@gated-at.bofh.it> (permalink)
References	(5 earlier) <tn5R7-5oQ-7@gated-at.bofh.it> <tn5R7-5oQ-5@gated-at.bofh.it> <tnyT8-8vM-7@gated-at.bofh.it> <tnzvQ-BH-3@gated-at.bofh.it> <tnBR0-266-33@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Tue, Mar 21, 2017 at 04:51:13PM -0700, Kees Cook wrote:
> On Tue, Mar 21, 2017 at 2:23 PM, Eric Dumazet <eric.dumazet@gmail.com> wrote:

> > Unfortunately there is no good test simulating real-world workloads,
> > which are mostly using TCP flows.
> 
> Sure, but there has to be _something_ that can be used to test to
> measure the effects. Without a meaningful test, it's weird to reject a
> change for performance reasons.

This. How can you optimize if there's no way to actually measure
something?

> > Most synthetic tools you can find are not using epoll(), and very often
> > hit bottlenecks in other layers.
> >
> >
> > It looks like our suggestion to get kernel builds with atomic_inc()
> > being exactly an atomic_inc() is not even discussed or implemented.
> 
> So, FWIW, I originally tried to make this a CONFIG in the first couple
> passes at getting a refcount defense. I would be fine with this, but I
> was not able to convince Peter. :) However, things have evolved a lot
> since then, so perhaps there are things do be done here.

Well, the argument was that unless there's a benchmark that shows it
cares, its all premature optimization.

Similarly, you wanted this enabled at all times because hardening.

Thread

[PATCH 00/17] net subsystem refcount conversions Elena Reshetova <elena.reshetova@intel.com> - 2017-03-16 16:30 +0100
  [PATCH 02/17] net: convert neigh_params.refcnt from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-16 16:30 +0100
  [PATCH 10/17] net: convert in_device.refcnt from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-16 16:40 +0100
  [PATCH 12/17] net: convert unix_address.refcnt from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-16 16:40 +0100
  [PATCH 14/17] net: convert inet_frag_queue.refcnt from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-16 16:40 +0100
  [PATCH 01/17] net: convert neighbour.refcnt from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-16 16:40 +0100
  [PATCH 11/17] net: convert netpoll_info.refcnt from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-16 16:40 +0100
  [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-16 16:40 +0100
    Re: [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to  refcount_t Eric Dumazet <eric.dumazet@gmail.com> - 2017-03-16 18:00 +0100
      Re: [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to refcount_t Kees Cook <keescook@chromium.org> - 2017-03-16 18:40 +0100
        Re: [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to  refcount_t David Miller <davem@davemloft.net> - 2017-03-16 20:20 +0100
          RE: [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to  refcount_t "Reshetova, Elena" <elena.reshetova@intel.com> - 2017-03-17 08:50 +0100
            Re: [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to  refcount_t Eric Dumazet <eric.dumazet@gmail.com> - 2017-03-17 17:20 +0100
              Re: [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to  refcount_t Herbert Xu <herbert@gondor.apana.org.au> - 2017-03-18 18:00 +0100
                Re: [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to  refcount_t David Miller <davem@davemloft.net> - 2017-03-19 02:40 +0100
                Re: [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to  refcount_t Peter Zijlstra <peterz@infradead.org> - 2017-03-20 11:50 +0100
                Re: [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to  refcount_t Peter Zijlstra <peterz@infradead.org> - 2017-03-20 14:30 +0100
                Re: [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to  refcount_t Peter Zijlstra <peterz@infradead.org> - 2017-03-20 14:50 +0100
                Re: [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to  refcount_t Eric Dumazet <eric.dumazet@gmail.com> - 2017-03-20 16:00 +0100
                Re: [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to  refcount_t Eric Dumazet <eric.dumazet@gmail.com> - 2017-03-20 17:20 +0100
                Re: [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to  refcount_t Eric Dumazet <eric.dumazet@gmail.com> - 2017-03-20 17:40 +0100
                Re: [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to  refcount_t Eric Dumazet <eric.dumazet@gmail.com> - 2017-03-20 16:30 +0100
                Re: [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to  refcount_t Peter Zijlstra <peterz@infradead.org> - 2017-03-20 16:50 +0100
                Re: [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to refcount_t Kees Cook <keescook@chromium.org> - 2017-03-21 21:50 +0100
                Re: [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to  refcount_t Eric Dumazet <eric.dumazet@gmail.com> - 2017-03-21 22:30 +0100
                Re: [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to  refcount_t David Miller <davem@davemloft.net> - 2017-03-21 23:40 +0100
                Re: [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to refcount_t Kees Cook <keescook@chromium.org> - 2017-03-22 01:00 +0100
                Re: [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to  refcount_t Eric Dumazet <eric.dumazet@gmail.com> - 2017-03-22 03:10 +0100
                Re: [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to  refcount_t Peter Zijlstra <peterz@infradead.org> - 2017-03-22 13:30 +0100
                Re: [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to  refcount_t Eric Dumazet <eric.dumazet@gmail.com> - 2017-03-22 14:30 +0100
                Re: [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to  refcount_t Peter Zijlstra <peterz@infradead.org> - 2017-03-22 15:40 +0100
                Re: [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to  refcount_t Eric Dumazet <eric.dumazet@gmail.com> - 2017-03-22 16:00 +0100
                Re: [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to  refcount_t Peter Zijlstra <peterz@infradead.org> - 2017-03-22 16:10 +0100
                Re: [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to  refcount_t Eric Dumazet <eric.dumazet@gmail.com> - 2017-03-22 16:30 +0100
                Re: [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to  refcount_t Peter Zijlstra <peterz@infradead.org> - 2017-03-22 18:00 +0100
                Re: [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to refcount_t Kees Cook <keescook@chromium.org> - 2017-03-22 20:10 +0100
                Re: [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to  refcount_t Peter Zijlstra <peterz@infradead.org> - 2017-03-22 14:50 +0100
                Re: [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to  refcount_t Herbert Xu <herbert@gondor.apana.org.au> - 2017-03-20 15:50 +0100
                Re: [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to  refcount_t Herbert Xu <herbert@gondor.apana.org.au> - 2017-03-20 14:50 +0100
                RE: [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to  refcount_t David Laight <David.Laight@ACULAB.COM> - 2017-03-20 15:20 +0100
                Re: [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to  refcount_t Peter Zijlstra <peterz@infradead.org> - 2017-03-20 15:30 +0100
                RE: [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to  refcount_t David Laight <David.Laight@ACULAB.COM> - 2017-03-20 16:10 +0100
  [PATCH 05/17] net: convert sk_buff_fclones.fclone_ref from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-16 16:40 +0100
  [PATCH 15/17] net: convert net.passive from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-16 16:40 +0100
  [PATCH 16/17] net: convert netlbl_lsm_cache.refcount from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-16 16:40 +0100
  [PATCH 09/17] net: convert ip_mc_list.refcnt from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-16 16:40 +0100
  [PATCH 04/17] net: convert sk_buff.users from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-16 16:40 +0100
  [PATCH 08/17] net: convert sk_filter.refcnt from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-16 16:40 +0100
    Re: [PATCH 08/17] net: convert sk_filter.refcnt from atomic_t to  refcount_t Daniel Borkmann <daniel@iogearbox.net> - 2017-03-16 17:10 +0100
      RE: [PATCH 08/17] net: convert sk_filter.refcnt from atomic_t to  refcount_t "Reshetova, Elena" <elena.reshetova@intel.com> - 2017-03-17 09:20 +0100
  [PATCH 17/17] net: convert packet_fanout.sk_ref from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-16 16:40 +0100
  [PATCH 06/17] net: convert sock.sk_wmem_alloc from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-16 16:40 +0100
  [PATCH 13/17] net: convert fib_rule.refcnt from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-16 16:40 +0100

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