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

["Dumitrescu, Cristian" <cristian.dumitrescu@intel.com>]

> -----Original Message-----
> From: Stephen Hemminger [mailto:stephen@networkplumber.org]
> Sent: Monday, February 9, 2015 10:55 PM
> To: Dumitrescu, Cristian
> Cc: dev@dpdk.org; Stephen Hemminger
> Subject: Re: [dpdk-dev] [PATCH v2 4/7] rte_sched: don't clear statistics when
> read
> 
> On Mon, 9 Feb 2015 22:48:36 +0000
> "Dumitrescu, Cristian" <cristian.dumitrescu@intel.com> wrote:
> 
> > Hi Stephen,
> >
> > What is the reason not to clear statistics on read? Do you have a use-case /
> justification for it?
> >
> > (BTW, I see you added the reset functions, but was it also your intention to
> remove the memset to 0 from the stats read functions? :) )
> >
> > Regards,
> > Cristian
> 
> Read and clear is a non-standard model. Interface statistics are not
> read/clear.
> We have lots of scripts that read statistics. Users don't like it if when
> stastics disappear.

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.
- When set to YES, we clear the stats counters on read. When set to NO, we do not clear stats counters on read;
- The default value for this configuration option should be YES, in order to preserve the backward compatibility with the current behavior;
- The stats reset functions introduced by this patch should always be enabled/compiled into the code, regardless of whether this new option is set to YES or NO.

What do you think?

Regards,
Cristian


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