From: Ivan Malov <ivan.malov@oktetlabs.ru>
Date: Tue, 1 Feb 2022 08:50:02 +0000 (+0300)
Subject: net/sfc: use even spread mode in flow action RSS
X-Git-Url: http://git.droids-corp.org/?a=commitdiff_plain;h=68cde2a3bd106934869205636c4399e0e02fdd38;p=dpdk.git

net/sfc: use even spread mode in flow action RSS

If the user provides contiguous ascending queue IDs,
use the even spread mode to avoid wasting resources
which are needed to serve indirection table entries.

Signed-off-by: Ivan Malov <ivan.malov@oktetlabs.ru>
Reviewed-by: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>
Reviewed-by: Andy Moreton <amoreton@xilinx.com>
---

diff --git a/drivers/net/sfc/sfc_flow_rss.c b/drivers/net/sfc/sfc_flow_rss.c
index 4bf3002164..e28c943335 100644
--- a/drivers/net/sfc/sfc_flow_rss.c
+++ b/drivers/net/sfc/sfc_flow_rss.c
@@ -140,6 +140,8 @@ sfc_flow_rss_parse_conf(struct sfc_adapter *sa,
 		return EINVAL;
 	}
 
+	out->rte_hash_function = in->func;
+
 	if (in->queue_num == 0) {
 		sfc_err(sa, "flow-rss: parse: 'queue_num' is 0; MIN=1");
 		return EINVAL;
@@ -317,6 +319,9 @@ sfc_flow_rss_ctx_program_tbl(struct sfc_adapter *sa,
 
 	SFC_ASSERT(sfc_adapter_is_locked(sa));
 
+	if (nb_tbl_entries == 0)
+		return 0;
+
 	if (conf->nb_qid_offsets != 0) {
 		SFC_ASSERT(ctx->qid_offsets != NULL);
 
@@ -336,6 +341,7 @@ sfc_flow_rss_ctx_program(struct sfc_adapter *sa, struct sfc_flow_rss_ctx *ctx)
 {
 	efx_rx_scale_context_type_t ctx_type = EFX_RX_SCALE_EXCLUSIVE;
 	struct sfc_adapter_shared * const sas = sfc_sa2shared(sa);
+	const efx_nic_cfg_t *encp = efx_nic_cfg_get(sa->nic);
 	const struct sfc_flow_rss *flow_rss = &sa->flow_rss;
 	struct sfc_rss *ethdev_rss = &sas->rss;
 	struct sfc_flow_rss_conf *conf;
@@ -366,6 +372,19 @@ sfc_flow_rss_ctx_program(struct sfc_adapter *sa, struct sfc_flow_rss_ctx *ctx)
 
 	nb_tbl_entries = RTE_MAX(flow_rss->nb_tbl_entries_min, nb_qid_offsets);
 
+	if (conf->rte_hash_function == RTE_ETH_HASH_FUNCTION_DEFAULT &&
+	    conf->nb_qid_offsets == 0 &&
+	    conf->qid_span <= encp->enc_rx_scale_even_spread_max_nqueues) {
+		/*
+		 * Conformance to a specific hash algorithm is a don't care to
+		 * the user. The queue array is contiguous and ascending. That
+		 * means that the even spread context may be requested here in
+		 * order to avoid wasting precious indirection table resources.
+		 */
+		ctx_type = EFX_RX_SCALE_EVEN_SPREAD;
+		nb_tbl_entries = 0;
+	}
+
 	if (ctx->nic_handle_refcnt == 0) {
 		rc = efx_rx_scale_context_alloc_v2(sa->nic, ctx_type,
 						   conf->qid_span,
diff --git a/drivers/net/sfc/sfc_flow_rss.h b/drivers/net/sfc/sfc_flow_rss.h
index 3341d06cf4..2ed81dc190 100644
--- a/drivers/net/sfc/sfc_flow_rss.h
+++ b/drivers/net/sfc/sfc_flow_rss.h
@@ -20,6 +20,7 @@ extern "C" {
 
 struct sfc_flow_rss_conf {
 	uint8_t				key[EFX_RSS_KEY_SIZE];
+	enum rte_eth_hash_function	rte_hash_function;
 	efx_rx_hash_type_t		efx_hash_types;
 	unsigned int			nb_qid_offsets;
 	unsigned int			qid_span;