Re: [dpdk-dev] [PATCH] [RFC, v2]: adds support PPS(packet per second) on meter

["Morten Brørup" <mb@smartsharesystems.com>]

> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Li Zhang
> Sent: Tuesday, February 23, 2021 3:07 AM
> 
> Thanks for your comments.
> We changed the struct as below:
> struct rte_mtr_meter_profile {
>  ......
> 		/** Items only valid when alg is set to sprTCM. */
> 		struct {
> 			/** Committed Information Packet Rate (CIPR). */
> 			uint64_t cipr;
> 
> 			/** Committed Packet Burst Size (CPBS). */
> 			uint64_t cpbs;
> 
> 			/** Excess Packet Burst Size (EPBS). */
> 			uint64_t epbs;
> 		} sprtcm;
> }

That is certainly not an improvement! Please stick with the broadly accepted industry standard names (CIR, CBS, EBS, etc.). Newly invented names like CIPR will only cause confusion. Please note that CIR, CBS, EBS don't say anything about their units; it could be bytes, packets, cells, frames, messages or anything else. So it is perfectly natural using the same names for packets instead of bytes.

I propose the following modifications instead.

For the algorithm, keep the "Single Rate Three Color Marker" name mentioned in the RFCs, but indicate that the variant is packet based:

	/** Single Rate Three Color Marker, Packet based (srTCMp). */
	RTE_MTR_SRTCMP,

Or if you prefer the packet based indicator at the front instead:

	/** Packet based Single Rate Three Color Marker (psrTCM). */
	RTE_MTR_PSRTCM,

And for the meter profile, keep the industry standard names, but update the descriptions:

 		/** Items only valid when *alg* is set to srTCMp. */
 		struct {
 			/** Committed Information Rate (CIR) (packets/second). */
 			uint64_t cir;
 
 			/** Committed Burst Size (CBS) (packets). */
 			uint64_t cbs;
 
 			/** Excess Burst Size (EBS) (packets). */
 			uint64_t ebs;
 		} srtcmp;


Come to think of it: Is the unit packets, or is it actually Ethernet frames? In other words: Does a 4 KB TCP packet that the NIC's offload function chops up into three Ethernet frames count as one or three in this algorithm?


Med venlig hilsen / kind regards
- Morten Brørup

> 
> Regards,
> Li Zhang
> > -----Original Message-----
> > From: dev <dev-bounces@dpdk.org> On Behalf Of Morten Br?rup
> > Sent: Friday, February 12, 2021 3:41 PM
> > To: Ferruh Yigit <ferruh.yigit@intel.com>; Li Zhang
> <lizh@nvidia.com>; Dekel
> > Peled <dekelp@nvidia.com>; Ori Kam <orika@nvidia.com>; Slava
> Ovsiienko
> > <viacheslavo@nvidia.com>; Matan Azrad <matan@nvidia.com>; Dumitrescu,
> > Cristian <cristian.dumitrescu@intel.com>
> > Cc: dev@dpdk.org; NBU-Contact-Thomas Monjalon <thomas@monjalon.net>;
> > Raslan Darawsheh <rasland@nvidia.com>
> > Subject: Re: [dpdk-dev] [PATCH] [RFC, v2]: adds support PPS(packet
> per second)
> > on meter
> >
> > > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Ferruh Yigit
> > > Sent: Thursday, January 28, 2021 7:28 PM
> > >
> > > On 1/25/2021 1:20 AM, Li Zhang wrote:
> > > > Currently the flow Meter algorithms in rte_flow only supports
> bytes
> > > > per second(BPS).
> > > > Such as Single Rate Three Color Marker (srTCM rfc2697) This RFC
> adds
> > > > the packet per second definition in Meter algorithms structure,
> to
> > > > support the rte_mtr APIs with type srTCM pps mode.
> > > > The below structure will be extended:
> > > > rte_mtr_algorithm
> > > > rte_mtr_meter_profile
> > > > Signed-off-by: Li Zhang <lizh@nvidia.com>
> > >
> > > cc'ed Cristian for review/comment.
> > >
> > > > ---
> > > >   lib/librte_ethdev/rte_mtr.h | 28 ++++++++++++++++++++++++++++
> > > >   1 file changed, 28 insertions(+)
> > > >
> > > > diff --git a/lib/librte_ethdev/rte_mtr.h
> > > b/lib/librte_ethdev/rte_mtr.h
> > > > index 916a09c5c3..3e88904faf 100644
> > > > --- a/lib/librte_ethdev/rte_mtr.h
> > > > +++ b/lib/librte_ethdev/rte_mtr.h
> > > > @@ -119,6 +119,9 @@ enum rte_mtr_algorithm {
> > > >
> > > >   	/** Two Rate Three Color Marker (trTCM) - IETF RFC 4115. */
> > > >   	RTE_MTR_TRTCM_RFC4115,
> > > > +
> > > > +	/** Single Rate Three Color Marker (srTCM) in Packet per
> second
> > > mode */
> > > > +	RTE_MTR_SRTCM_PPS,
> > > >   };
> > > >
> > > >   /**
> > > > @@ -171,6 +174,18 @@ struct rte_mtr_meter_profile {
> > > >   			/** Excess Burst Size (EBS) (bytes). */
> > > >   			uint64_t ebs;
> > > >   		} trtcm_rfc4115;
> > > > +
> > > > +		/** Items only valid when *alg* is set to srTCM -
> PPS. */
> > > > +		struct {
> > > > +			/** Committed Information Rate
> > (CIR)(packets/second).
> > > */
> > > > +			uint64_t cir;
> > > > +
> > > > +			/** Committed Burst Size (CBS) (bytes). */
> > > > +			uint64_t cbs;
> > > > +
> > > > +			/** Excess Burst Size (EBS) (bytes). */
> > > > +			uint64_t ebs;
> > > > +		} srtcm_pps;
> >
> > In PPS mode, the burst sizes (ebs, ebs) must be packets, not bytes.
> >
> > > >   	};
> > > >   };
> > > >
> > > > @@ -317,6 +332,13 @@ struct rte_mtr_capabilities {
> > > >   	 */
> > > >   	uint32_t meter_trtcm_rfc4115_n_max;
> > > >
> > > > +	/** Maximum number of MTR objects that can have their meter
> > > configured
> > > > +	 * to run the srTCM packet per second algorithm. The value
> of 0
> > > > +	 * indicates this metering algorithm is not supported.
> > > > +	 * The maximum value is *n_max*.
> > > > +	 */
> > > > +	uint32_t meter_srtcm_pps_n_max;
> > > > +
> > > >   	/** Maximum traffic rate that can be metered by a single
> MTR
> > > object. For
> > > >   	 * srTCM RFC 2697, this is the maximum CIR rate. For trTCM
> RFC
> > > 2698,
> > > >   	 * this is the maximum PIR rate. For trTCM RFC 4115, this
> is the
> > > maximum
> > > > @@ -342,6 +364,12 @@ struct rte_mtr_capabilities {
> > > >   	 */
> > > >   	int color_aware_trtcm_rfc4115_supported;
> > > >
> > > > +	/**
> > > > +	 * When non-zero, it indicates that color aware mode is
> supported
> > > for
> > > > +	 * the srTCM packet per second  metering algorithm.
> >
> > No need for two spaces between the words second and metering.
> >
> > > > +	 */
> > > > +	int color_aware_srtcm_pps_supported;
> > > > +
> > > >   	/** When non-zero, it indicates that the policer packet
> recolor
> > > actions
> > > >   	 * are supported.
> > > >   	 * @see enum rte_mtr_policer_action
> > > >
> > >