Re: [dpdk-dev] meter: excess token bucket update in srtcm

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

Thanks, Nikhil, will review and get back to you in the next couple of weeks. Regards, Cristian

From: Nikhil Jagtap [mailto:nikhil.jagtap@gmail.com]
Sent: Wednesday, September 7, 2016 7:22 AM
To: Dumitrescu, Cristian <cristian.dumitrescu@intel.com>
Cc: Ramia, Kannan Babu <kannan.babu.ramia@intel.com>; dev@dpdk.org
Subject: Re: [dpdk-dev] meter: excess token bucket update in srtcm

Hi Cristian,

Thanks for the confirmation. I have submitted a patch for the same.
http://dpdk.org/ml/archives/dev/2016-September/046226.html

Regards,
Nikhil

On 6 September 2016 at 15:26, Dumitrescu, Cristian <cristian.dumitrescu@intel.com<mailto:cristian.dumitrescu@intel.com>> wrote:
Hi Nikhil,

It also looks to me that you are right. Sorry, my mistake when translating the RFC into code.

Challenge in fixing this is how to code it using minimal number of branches ...

Thanks,
Cristian

> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org<mailto:dev-bounces@dpdk.org>] On Behalf Of Nikhil Jagtap
> Sent: Tuesday, September 6, 2016 7:30 AM
> To: Ramia, Kannan Babu <kannan.babu.ramia@intel.com<mailto:kannan.babu.ramia@intel.com>>
> Cc: dev@dpdk.org<mailto:dev@dpdk.org>
> Subject: Re: [dpdk-dev] meter: excess token bucket update in srtcm
>
> Hi Kannan,
>
> Thank you for your reply. I will submit the patch on similar lines I had
> used for my test.
>
> Regards,
> Nikhil
>
> On 6 September 2016 at 10:40, Ramia, Kannan Babu <
> kannan.babu.ramia@intel.com<mailto:kannan.babu.ramia@intel.com>> wrote:
>
> > Hi Nikhil
> >
> > You could submit a patch, something like that below logic
> >
> > If( ((n_periods * m->cir_bytes_per_period) > (m->cbs-m->tc))
> >         te = m->te + ((n_periods * m->cir_bytes_per_period) -
> > (m->cbs-m->tc));
> >
> > and this should be done before m->tc update.
> >
> >
> > Regards
> > Kannan Babu
> >
> > -----Original Message-----
> > From: dev [mailto:dev-bounces@dpdk.org<mailto:dev-bounces@dpdk.org>] On Behalf Of Nikhil Jagtap
> > Sent: Tuesday, September 6, 2016 9:43 AM
> > To: Dumitrescu, Cristian <cristian.dumitrescu@intel.com<mailto:cristian.dumitrescu@intel.com>>
> > Cc: dev@dpdk.org<mailto:dev@dpdk.org>
> > Subject: Re: [dpdk-dev] meter: excess token bucket update in srtcm
> >
> > Hi,
> > Can someone please comment on this?
> >
> > Nikhil
> >
> > On 31 August 2016 at 15:32, Nikhil Jagtap <nikhil.jagtap@gmail.com<mailto:nikhil.jagtap@gmail.com>> wrote:
> >
> > > Hi,
> > >
> > > As per srTCM RFC 2697, we should be updating the E bucket only after
> > > the C bucket overflows.
> > > "Thereafter, the token counts Tc and Te are updated CIR times per
> > > second as follows:
> > >      o If Tc is less than CBS, Tc is incremented by one, else
> > >      o if Te is less then EBS, Te is incremented by one, else
> > >      o neither Tc nor Te is incremented."
> > >
> > > However in the current DPDK implementation of srTCM, we are updating
> > > both the buckets simultaneously at the same rate (CIR). This will
> > > result in a token accumulation rate of (2*CIR). This seems like a bug
> > > to me. Can you confirm this?
> > >
> > > Nikhil
> > >
> > >
> >