Re: [dpdk-dev] [PATCH v2] ethdev: support double precision RED queue weight

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

> -----Original Message-----
> From: Rao, Nikhil
> Sent: Thursday, January 10, 2019 4:36 PM
> To: Dumitrescu, Cristian <cristian.dumitrescu@intel.com>; Singh, Jasvinder
> <jasvinder.singh@intel.com>
> Cc: Lu, Wenzhuo <wenzhuo.lu@intel.com>; Wu, Jingjing
> <jingjing.wu@intel.com>; Iremonger, Bernard
> <bernard.iremonger@intel.com>; dev@dpdk.org; Rao, Nikhil
> <nikhil.rao@intel.com>
> Subject: [PATCH v2] ethdev: support double precision RED queue weight
> 
> RED queue weight is currently specified as a negated log of 2.
> 
> Add support for RED queue weight to be specified in double precision
> and TM capability flags for double precision and negated log2
> RED queue weight support.
> 
> Update the softnic PMD and testpmd for the new tm capability flags and
> the struct rte_tm_red_params::wq_is_log2 flag.
> 
> Signed-off-by: Nikhil Rao <nikhil.rao@intel.com>
> ---
>  lib/librte_ethdev/rte_tm.h               | 40
> ++++++++++++++++++++++++++++++--
>  app/test-pmd/cmdline_tm.c                |  8 ++++++-
>  drivers/net/softnic/rte_eth_softnic_tm.c |  7 ++++--
>  3 files changed, 50 insertions(+), 5 deletions(-)
> 
> v2:
> * added RTE_STD_C11 for anonymnous union
> * testpmd: added cman_wred_wq_log2/wq_dp_supported to "show port
> tm cap" cli command
> * testpmd: set wq_is_log2 for WRED profiles added on testpmd cli
> 
> Cristian,
> I assume the testpmd changes will be upstreamed via the dpdk-next-qos
> tree.
> 
> diff --git a/lib/librte_ethdev/rte_tm.h b/lib/librte_ethdev/rte_tm.h
> index c4a788b..4fad31b 100644
> --- a/lib/librte_ethdev/rte_tm.h
> +++ b/lib/librte_ethdev/rte_tm.h
> @@ -391,6 +391,22 @@ struct rte_tm_capabilities {
>  	 */
>  	int cman_wred_byte_mode_supported;
> 
> +	/** Double precision RED queue weight support. When non-zero,
> this
> +	 * this parameter indicates that RED queue weight in double precision
> +	 * format is supported.
> +	 * @see struct rte_tm_red_params::wq_is_log2
> +	 * @see struct rte_tm_red_params::wq_dp
> +	 */
> +	int cman_wred_wq_dp_supported;
> +
> +	/** Negated log2 RED queue weight support. When non-zero, this
> +	 * parameter indicates that RED queue weight in negated log2 format
> +	 * is supported.
> +	 * @see struct rte_tm_red_params::wq_is_log2
> +	 * @see struct rte_tm_red_params::wq_log2
> +	 */
> +	int cman_wred_wq_log2_supported;
> +
>  	/** Head drop algorithm support. When non-zero, this parameter
>  	 * indicates that there is at least one leaf node that supports the
> head
>  	 * drop algorithm, which might not be true for all the leaf nodes.
> @@ -839,8 +855,28 @@ struct rte_tm_red_params {
>  	 */
>  	uint16_t maxp_inv;
> 
> -	/** Negated log2 of queue weight (wq), i.e. wq = 1 / (2 ^ wq_log2)
> */
> -	uint16_t wq_log2;
> +	/** When non-zero, RED queue weight (wq) is negated log2 of
> queue
> +	 * weight
> +	 *
> +	 * @see struct rte_tm_capabilities::cman_wred_wq_dp_supported
> +	 * @see struct rte_tm_capabilities::cman_wred_wq_log2_supported
> +	 */
> +	int wq_is_log2;
> +
> +	RTE_STD_C11
> +	union {
> +		/** Double precision queue weight
> +		 *
> +		 * @see struct
> rte_tm_capabilities::cman_wred_wq_dp_supported
> +		 */
> +		double wq_dp;
> +		/** Negated log2 of queue weight (wq),
> +		 * i.e. wq = 1 / (2 ^ wq_log2)
> +		 *
> +		 * @see struct
> rte_tm_capabilities::cman_wred_wq_log2_supported
> +		 */
> +		uint16_t wq_log2;
> +	};
>  };
> 
>  /**
> diff --git a/app/test-pmd/cmdline_tm.c b/app/test-pmd/cmdline_tm.c
> index 1012084..afc1d63 100644
> --- a/app/test-pmd/cmdline_tm.c
> +++ b/app/test-pmd/cmdline_tm.c
> @@ -283,6 +283,10 @@ static void cmd_show_port_tm_cap_parsed(void
> *parsed_result,
>  		cap.sched_wfq_n_groups_max);
>  	printf("cap.sched_wfq_weight_max %" PRIu32 "\n",
>  		cap.sched_wfq_weight_max);
> +	printf("cap.cman_wred_wq_dp_supported %" PRId32 "\n",
> +		cap.cman_wred_wq_dp_supported);
> +	printf("cap.cman_wred_wq_log2_supported %" PRId32 "\n",
> +		cap.cman_wred_wq_log2_supported);
>  	printf("cap.cman_head_drop_supported %" PRId32 "\n",
>  		cap.cman_head_drop_supported);
>  	printf("cap.cman_wred_context_n_max %" PRIu32 "\n",
> @@ -1285,7 +1289,7 @@ static void
> cmd_add_port_tm_node_wred_profile_parsed(void *parsed_result,
>  	wp.red_params[color].max_th = res->max_th_g;
>  	wp.red_params[color].maxp_inv = res->maxp_inv_g;
>  	wp.red_params[color].wq_log2 = res->wq_log2_g;
> -
> +	wp.red_params[color].wq_is_log2 = 1;
> 
>  	/* WRED Params  (Yellow Color)*/
>  	color = RTE_TM_YELLOW;
> @@ -1293,6 +1297,7 @@ static void
> cmd_add_port_tm_node_wred_profile_parsed(void *parsed_result,
>  	wp.red_params[color].max_th = res->max_th_y;
>  	wp.red_params[color].maxp_inv = res->maxp_inv_y;
>  	wp.red_params[color].wq_log2 = res->wq_log2_y;
> +	wp.red_params[color].wq_is_log2 = 1;
> 
>  	/* WRED Params  (Red Color)*/
>  	color = RTE_TM_RED;
> @@ -1300,6 +1305,7 @@ static void
> cmd_add_port_tm_node_wred_profile_parsed(void *parsed_result,
>  	wp.red_params[color].max_th = res->max_th_r;
>  	wp.red_params[color].maxp_inv = res->maxp_inv_r;
>  	wp.red_params[color].wq_log2 = res->wq_log2_r;
> +	wp.red_params[color].wq_is_log2 = 1;
> 
>  	ret = rte_tm_wred_profile_add(port_id, wred_profile_id, &wp,
> &error);
>  	if (ret != 0) {
> diff --git a/drivers/net/softnic/rte_eth_softnic_tm.c
> b/drivers/net/softnic/rte_eth_softnic_tm.c
> index baaafbe..e96ea8e 100644
> --- a/drivers/net/softnic/rte_eth_softnic_tm.c
> +++ b/drivers/net/softnic/rte_eth_softnic_tm.c
> @@ -469,7 +469,8 @@ struct softnic_tmgr_port *
>  	.cman_wred_context_shared_n_max = 0,
>  	.cman_wred_context_shared_n_nodes_per_context_max = 0,
>  	.cman_wred_context_shared_n_contexts_per_node_max = 0,
> -
> +	.cman_wred_wq_dp_supported = 0,
> +	.cman_wred_wq_log2_supported = WRED_SUPPORTED,
>  	.mark_vlan_dei_supported = {0, 0, 0},
>  	.mark_ip_ecn_tcp_supported = {0, 0, 0},
>  	.mark_ip_ecn_sctp_supported = {0, 0, 0},
> @@ -1243,8 +1244,10 @@ struct softnic_tmgr_port *
>  	for (color = RTE_TM_GREEN; color < RTE_TM_COLORS; color++) {
>  		uint32_t min_th = profile->red_params[color].min_th;
>  		uint32_t max_th = profile->red_params[color].max_th;
> +		int wq_is_log2 = profile->red_params[color].wq_is_log2;
> 
> -		if (min_th > max_th ||
> +		if (wq_is_log2 == 0 ||
> +			min_th > max_th ||
>  			max_th == 0 ||
>  			min_th > UINT16_MAX ||
>  			max_th > UINT16_MAX)
> --
> 1.8.3.1


Hi Nikhil,

Code looks good to me, but there is a problem: you are introducing new API without providing an implementation for it, and this is no longer allowed by the DPDK Tech Board [1][2].

Would it be possible to provide an implementation for this new API? A SW implementation in librte_sched/rte_red.[hc] or divers/net/softnic would be enough to tick this box.

Thanks,
Cristian

[1] https://mails.dpdk.org/archives/dev/2018-December/122213.html
[2] https://mails.dpdk.org/archives/dev/2018-November/118697.html