Re: [PATCH net-next iproute2] iplink: display rx nohandler stats

From	Eric Dumazet <eric.dumazet@gmail.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH net-next iproute2] iplink: display rx nohandler stats
Date	2016-02-10 06:00 +0100
Message-ID	<r0v2F-5RT-3@gated-at.bofh.it> (permalink)
References	(3 earlier) <r0c9H-1Bp-13@gated-at.bofh.it> <r0ebw-2Tw-11@gated-at.bofh.it> <r0lZo-8lW-13@gated-at.bofh.it> <r0qmm-2FL-1@gated-at.bofh.it> <r0s4O-3QG-21@gated-at.bofh.it>
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On Tue, 2016-02-09 at 17:41 -0800, Stephen Hemminger wrote:
> On Tue, 9 Feb 2016 18:51:35 -0500
> Jarod Wilson <jarod@redhat.com> wrote:
> 
> > On Tue, Feb 09, 2016 at 11:17:57AM -0800, Stephen Hemminger wrote:
> > > Support for the new rx_nohandler statistic.
> > > This code is designed to handle the case where the kernel reported statistic
> > > structure is smaller than the larger structure in later releases (and vice versa).
> > 
> > This seems to work here, for the most part. However, if you are running a
> > kernel with the new counter, and the counter happens to contain 0, aren't
> > we going to not print anything?
> 
> That is the desirable outcome, since if run on older system the
> output format will not change from current format.

The problem here is that a change in output might break some user
scripts using sed/whatever games.

So it might be better to output a zero field, so that such breakages are
detected early, even if no packet was dropped at the time the new kernel
was tested.

Having a binary that adds the new field only in some cases hides the
change. It looks fine for us humans, but not for programs processing the
output.

Thread

Re: [PATCH net v3 2/4] net: add rx_nohandler stat counter Jamal Hadi Salim <jhs@mojatatu.com> - 2016-02-09 12:00 +0100
  [PATCH net-next iproute2] iplink: display rx nohandler stats Stephen Hemminger <stephen@networkplumber.org> - 2016-02-09 20:20 +0100
    Re: [PATCH net-next iproute2] iplink: display rx nohandler stats Jarod Wilson <jarod@redhat.com> - 2016-02-10 01:00 +0100
      Re: [PATCH net-next iproute2] iplink: display rx nohandler stats Stephen Hemminger <stephen@networkplumber.org> - 2016-02-10 02:50 +0100
        Re: [PATCH net-next iproute2] iplink: display rx nohandler stats Eric Dumazet <eric.dumazet@gmail.com> - 2016-02-10 06:00 +0100
          Re: [PATCH net-next iproute2] iplink: display rx nohandler stats Jarod Wilson <jarod@redhat.com> - 2016-02-10 14:30 +0100
            Re: [PATCH net-next iproute2] iplink: display rx nohandler stats Andy Gospodarek <gospo@cumulusnetworks.com> - 2016-02-10 16:10 +0100

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