Re: [PATCH v2 4/7] rte_sched: don't clear statistics when read

[Thomas Monjalon <thomas.monjalon-pdR9zngts4EAvxtiuMwx3w@public.gmane.org>]

2015-02-20 20:23, Dumitrescu, Cristian:
> From: Stephen Hemminger [mailto:stephen-OTpzqLSitTUnbdJkjeBofR2eb7JE58TQ@public.gmane.org]
> > On Fri, 20 Feb 2015 18:32:03 +0000
> > "Dumitrescu, Cristian" <cristian.dumitrescu-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org> wrote:
> > 
> > > Stephen, I suggest adding a new build-time configuration option for the
> > > librte_sched library in config/common_* files:
> > > CONFIG_RTE_SCHED_STATS_CLEAR_ON_READ.
> > 
> > Build time config options do not work for distributions.
> 
> Why?
> 
> This does not affect the API, as the new API functions are always compiled
> in, and the prototypes are not changed, and no data structures are affected.

Behaviour is an important part of the API. Think comments as part of the API.

> This only changes the behavior of certain functions, so that user can
> select which mode it needs.

When user doesn't or cannot rebuild, he has no choice.

> It also preserves backward compatibility.
> 
> We have so many compilation options in config file, why is this one different?

We must remove and avoid build-time options.
The only ones which might be acceptable are the ones which allow more
performance by disabling some features.

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