RE: Fwd: QOS sample example.

["Singh, Jasvinder" <jasvinder.singh@intel.com>]

> -----Original Message-----
> From: Thomas Monjalon <thomas@monjalon.net>
> Sent: Thursday, March 31, 2022 8:39 PM
> To: satish amara <satishkamara@gmail.com>
> Cc: users@dpdk.org; Singh, Jasvinder <jasvinder.singh@intel.com>;
> Dumitrescu, Cristian <cristian.dumitrescu@intel.com>
> Subject: Re: Fwd: QOS sample example.
> 
> +Cc QoS scheduler maintainers (see file MAINTAINERS)
> 
> 31/03/2022 18:59, satish amara:
> > Hi,
> >     I am trying to understand the QOS sample scheduler application code.
> > Trying to understand what is tc_period in the config.
> > 30. QoS Scheduler Sample Application — Data Plane Development Kit
> > 21.05.0 documentation (dpdk.org)
> > <https://doc.dpdk.org/guides-
> 21.05/sample_app_ug/qos_scheduler.html>
> > Is tc_period same as  tb_period tb_period Bytes Time period that
> > should elapse since the last credit update in order for the bucket to
> > be awarded tb_credits_per_period worth or credits.
> > Regards,
> > Satish Amara
> >

tc_period and tb_period are different. TC period is related to pipe tc rate limiting mechanism while tb period relates to traffic shaping mechanism (token bucket) implemented at pipe level.  tc_period represents the time interval to compute pipe TC credits (bytes). In each interval (tc_period value), credits are initialised to a fixed value. It is configurable parameter and should be carefully selected to avoid deadlock situation which arises when number of pipe TC credits (computed using tc_period) is smaller than the MTU. Please refer  https://doc.dpdk.org/guides/prog_guide/qos_framework.html for more details.