[dpdk-dev] [PATCH v7 5/6] lib: added new library for latency stats

[Mcnamara, John]

> -----Original Message-----
> From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Jerin Jacob
> Sent: Tuesday, January 17, 2017 4:30 AM
> To: Horton, Remy <remy.horton at intel.com>
> Cc: dev at dpdk.org; Pattan, Reshma <reshma.pattan at intel.com>; Thomas
> Monjalon <thomas.monjalon at 6wind.com>
> Subject: Re: [dpdk-dev] [PATCH v7 5/6] lib: added new library for latency
> stats
> 
> On Mon, Jan 16, 2017 at 04:19:32PM +0000, Remy Horton wrote:
> > From: Reshma Pattan <reshma.pattan at intel.com>
> >
> > Add a library designed to calculate latency statistics and report them
> > to the application when queried. The library measures minimum, average
> > and maximum latencies, and jitter in nano seconds. The current
> > implementation supports global latency stats, i.e. per application
> stats.
> >
> > Signed-off-by: Reshma Pattan <reshma.pattan at intel.com>
> > Signed-off-by: Remy Horton <remy.horton at intel.com>
> > ---
> >  MAINTAINERS                                        |   4 +
> >  config/common_base                                 |   5 +
> >  doc/api/doxy-api-index.md                          |   1 +
> >  doc/api/doxy-api.conf                              |   1 +
> >  doc/guides/rel_notes/release_17_02.rst             |   5 +
> >  lib/Makefile                                       |   1 +
> >  lib/librte_latencystats/Makefile                   |  57 +++
> >  lib/librte_latencystats/rte_latencystats.c         | 389
> +++++++++++++++++++++
> >  lib/librte_latencystats/rte_latencystats.h         | 146 ++++++++
> >  .../rte_latencystats_version.map                   |  10 +
> >  lib/librte_mbuf/rte_mbuf.h                         |   3 +
> 
> It is a value added feature for DPDK. But what is the plan for
> incorporating the mbuf change? I have 8 month old mbuf change for ARM for
> natural alignment. If we are accepting any mbuf change then we need to
> include outstanding mbuf changes to avoid future ABI breakage.
> 
> http://dpdk.org/dev/patchwork/patch/12878/
> 

Hi Jerin,

As far as I know the plan was to reach some sort of consensus on the mbuf
structure at the DPDK Userspace 2016, during and after Olivier's
presentation and then to make those changes during 17.02.

However, I believe Olivier had other work commitments in this release and
wasn't able to work on the mbuf changes.

The above mbuf change (and addition at the end of the struct) should
have gone into that mbuf rework, along with your changes.

However, since the mbuf rework didn't happen we need to add the field in
this release.

I guess the difference between the above change and your change is that
the latter is more complex and potentially affect performance, and as such
makes more sense as part of a rework.

Perhaps we, as a community, should commit to the mbuf rework in 17.05
and make sure it gets done.

John