Re: [dpdk-dev] [PATCH v3] ethdev: add tm support for shaper config in pkt mode

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

Hi Nithin,

> -----Original Message-----
> From: Nithin Dabilpuram <nithind1988@gmail.com>
> Sent: Wednesday, April 22, 2020 9:00 AM
> To: Singh, Jasvinder <jasvinder.singh@intel.com>; Dumitrescu, Cristian
> <cristian.dumitrescu@intel.com>; Thomas Monjalon
> <thomas@monjalon.net>; Yigit, Ferruh <ferruh.yigit@intel.com>; Andrew
> Rybchenko <arybchenko@solarflare.com>
> Cc: dev@dpdk.org; jerinj@marvell.com; kkanas@marvell.com; Nithin
> Dabilpuram <ndabilpuram@marvell.com>
> Subject: [PATCH v3] ethdev: add tm support for shaper config in pkt mode
> 
> From: Nithin Dabilpuram <ndabilpuram@marvell.com>
> 
> Some NIC hardware support shaper to work in packet mode i.e
> shaping or ratelimiting traffic is in packets per second (PPS) as
> opposed to default bytes per second (BPS). Hence this patch
> adds support to configure shared or private shaper in packet mode,
> provide rate in PPS and add related tm capabilities in port/level/node
> capability structures.
> 
> This patch also updates tm port/level/node capability structures with
> exiting features of scheduler wfq packet mode, scheduler wfq byte mode
> and private/shared shaper byte mode.
> 
> SoftNIC PMD is also updated with new capabilities.
> 
> Signed-off-by: Nithin Dabilpuram <ndabilpuram@marvell.com>
> ---
> 
> v2..v3:
> - Fix typo's
> - Add shaper_shared_(packet, byte)_mode_supported in level and node cap
> - Fix comment in pkt_length_adjust.
> - Move rte_eth_softnic_tm.c capability update to patch 1/4 to
>   avoid compilations issues in node and level cap array in softnicpmd.
>   ../drivers/net/softnic/rte_eth_softnic_tm.c:782:3: warning: braces around
> scalar initializer
>    {.nonleaf = {
>   ../drivers/net/softnic/rte_eth_softnic_tm.c:782:3: note: (near initialization
> for ‘tm_node_cap[0].shaper_shared_byte_mode_supported’)
>   ../drivers/net/softnic/rte_eth_softnic_tm.c:782:4: error: field name not in
> record or union initializer
>    {.nonleaf = {
> 
> v1..v2:
> - Add seperate capability for shaper and scheduler pktmode and bytemode.
> - Add packet_mode field in struct rte_tm_shaper_params to indicate
> packet mode shaper profile.
> 
> 
>  drivers/net/softnic/rte_eth_softnic_tm.c |  65 ++++++++++
>  lib/librte_ethdev/rte_tm.h               | 196
> ++++++++++++++++++++++++++++++-
>  2 files changed, 259 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/softnic/rte_eth_softnic_tm.c
> b/drivers/net/softnic/rte_eth_softnic_tm.c
> index 80a470c..344819f 100644
> --- a/drivers/net/softnic/rte_eth_softnic_tm.c
> +++ b/drivers/net/softnic/rte_eth_softnic_tm.c

<snip>...

The softnic changes logically belong to a separate patch. I understand you are getting some build warnings, but it does not make sense to me. Are you sure there is no other way to avoid them?

You are not checking that packet_mode is set to 0. Please add a check in function shaper_profile_check() (file rte_eth_softnic_tm.c) to verify that packet_mode is always set to 0.

Jasvinder, any other changes we need in Soft NIC?

> diff --git a/lib/librte_ethdev/rte_tm.h b/lib/librte_ethdev/rte_tm.h
> index f9c0cf3..b3865af 100644
> --- a/lib/librte_ethdev/rte_tm.h
> +++ b/lib/librte_ethdev/rte_tm.h

I am now fine with your additions to this file, with some minor exceptions listed below. Thank you!

> @@ -250,6 +250,23 @@ struct rte_tm_capabilities {
>  	 */
>  	uint64_t shaper_private_rate_max;
> 
> +	/** Shaper private packet mode supported. When non-zero, this
> parameter
> +	 * indicates that there is at least one node that can be configured
> +	 * with packet mode in it's private shaper. When shaper is configured

Recurring typo: it's -> its

Please search for all occurrences of "it's", all should be replaced with either "its" or "it is", we should have absolutely no occurrence of "it's".

<snip>...

> 
> @@ -860,6 +1034,11 @@ struct rte_tm_token_bucket {
>   * Dual rate shapers use both the committed and the peak token buckets.
> The
>   * rate of the peak bucket has to be bigger than zero, as well as greater than
>   * or equal to the rate of the committed bucket.
> + *
> + * @see struct
> rte_tm_capabilities::shaper_private_packet_mode_supported
> + * @see struct rte_tm_capabilities::shaper_private_byte_mode_supported
> + * @see struct
> rte_tm_capabilities::shaper_shared_packet_mode_supported
> + * @see struct rte_tm_capabilities::shaper_shared_byte_mode_supported
>   */
>  struct rte_tm_shaper_params {
>  	/** Committed token bucket */
> @@ -872,8 +1051,19 @@ struct rte_tm_shaper_params {
>  	 * purpose of shaping. Can be used to correct the packet length with
>  	 * the framing overhead bytes that are also consumed on the wire
> (e.g.
>  	 * RTE_TM_ETH_FRAMING_OVERHEAD_FCS).
> +	 * This field is ignored when the profile enables packet mode.
>  	 */
>  	int32_t pkt_length_adjust;
> +
> +	/** When zero, the private or shared shaper that is associated to this
> +	 * profile works in byte mode and hence *rate* and *size* fields in
> +	 * both token bucket configurations are specified in bytes per second
> +	 * and bytes respectively.
> +	 * When non-zero, that private or shared shaper works in packet
> mode and
> +	 * hence *rate* and *size* fields in both token bucket configurations
> +	 * are specified in packets per second and packets respectively.
> +	 */
> +	int packet_mode;
>  };

I would like to simplify this comment a bit. The reference to a shaper being associated with a profile might be confusing, as some people might incorrectly read there is a 1:1 association between shaper and profile, etc; this is described in mode details in the comment at the top of this structure. I would avoid any mentions of objects outside of the current structure.

I would phrase it like: "When zero, the byte mode is enabled for the current profile, so the *rate* and *size* fields in both the committed and peak token buckets are specified in bytes per second and bytes, respectively. When non-zero, the packet mode is enabled for the current profile, so the *rate* and *size* fields in both the committed and peak token buckets are specified in packets per second and packets, respectively. ". Is this OK with you?

Please also add the links to the relevant capabilities: @see struct rte_tm_node_capabilities::XYZ.


Regards,
Cristian