[dpdk-dev] [PATCH v2 1/6] cxgbe: Optimize forwarding performance for 40G

[Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>]

Update sge initialization with respect to free-list manager configuration
and ingress arbiter. Also update refill logic to refill mbufs only after
a certain threshold for rx.  Optimize tx packet prefetch.

Approx. 3 MPPS improvement seen in forwarding performance after the
optimization.

Signed-off-by: Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>
Signed-off-by: Kumar Sanghvi <kumaras@chelsio.com>
---
v2:
- Don't re-define rte_pktmbuf_free() locally.  Thanks to review by
  Aaron Conole <aconole@redhat.com> and Konstantin Ananyev
  <konstantin.ananyev@intel.com>

 drivers/net/cxgbe/base/t4_regs.h | 16 ++++++++++++++++
 drivers/net/cxgbe/cxgbe_main.c   |  7 +++++++
 drivers/net/cxgbe/sge.c          |  8 ++++----
 3 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/drivers/net/cxgbe/base/t4_regs.h b/drivers/net/cxgbe/base/t4_regs.h
index cd28b59..9057e40 100644
--- a/drivers/net/cxgbe/base/t4_regs.h
+++ b/drivers/net/cxgbe/base/t4_regs.h
@@ -266,6 +266,18 @@
 #define A_SGE_FL_BUFFER_SIZE2 0x104c
 #define A_SGE_FL_BUFFER_SIZE3 0x1050
 
+#define A_SGE_FLM_CFG 0x1090
+
+#define S_CREDITCNT    4
+#define M_CREDITCNT    0x3U
+#define V_CREDITCNT(x) ((x) << S_CREDITCNT)
+#define G_CREDITCNT(x) (((x) >> S_CREDITCNT) & M_CREDITCNT)
+
+#define S_CREDITCNTPACKING    2
+#define M_CREDITCNTPACKING    0x3U
+#define V_CREDITCNTPACKING(x) ((x) << S_CREDITCNTPACKING)
+#define G_CREDITCNTPACKING(x) (((x) >> S_CREDITCNTPACKING) & M_CREDITCNTPACKING)
+
 #define A_SGE_CONM_CTRL 0x1094
 
 #define S_EGRTHRESHOLD    8
@@ -361,6 +373,10 @@
 
 #define A_SGE_CONTROL2 0x1124
 
+#define S_IDMAARBROUNDROBIN    19
+#define V_IDMAARBROUNDROBIN(x) ((x) << S_IDMAARBROUNDROBIN)
+#define F_IDMAARBROUNDROBIN    V_IDMAARBROUNDROBIN(1U)
+
 #define S_INGPACKBOUNDARY    16
 #define M_INGPACKBOUNDARY    0x7U
 #define V_INGPACKBOUNDARY(x) ((x) << S_INGPACKBOUNDARY)
diff --git a/drivers/net/cxgbe/cxgbe_main.c b/drivers/net/cxgbe/cxgbe_main.c
index 3755444..316b87d 100644
--- a/drivers/net/cxgbe/cxgbe_main.c
+++ b/drivers/net/cxgbe/cxgbe_main.c
@@ -422,6 +422,13 @@ static int adap_init0_tweaks(struct adapter *adapter)
 	t4_set_reg_field(adapter, A_SGE_CONTROL, V_PKTSHIFT(M_PKTSHIFT),
 			 V_PKTSHIFT(rx_dma_offset));
 
+	t4_set_reg_field(adapter, A_SGE_FLM_CFG,
+			 V_CREDITCNT(M_CREDITCNT) | M_CREDITCNTPACKING,
+			 V_CREDITCNT(3) | V_CREDITCNTPACKING(1));
+
+	t4_set_reg_field(adapter, A_SGE_CONTROL2, V_IDMAARBROUNDROBIN(1U),
+			 V_IDMAARBROUNDROBIN(1U));
+
 	/*
 	 * Don't include the "IP Pseudo Header" in CPL_RX_PKT checksums: Linux
 	 * adds the pseudo header itself.
diff --git a/drivers/net/cxgbe/sge.c b/drivers/net/cxgbe/sge.c
index 6eb1244..69ab487 100644
--- a/drivers/net/cxgbe/sge.c
+++ b/drivers/net/cxgbe/sge.c
@@ -286,8 +286,7 @@ static void unmap_rx_buf(struct sge_fl *q)
 
 static inline void ring_fl_db(struct adapter *adap, struct sge_fl *q)
 {
-	/* see if we have exceeded q->size / 4 */
-	if (q->pend_cred >= (q->size / 4)) {
+	if (q->pend_cred >= 64) {
 		u32 val = adap->params.arch.sge_fl_db;
 
 		if (is_t4(adap->params.chip))
@@ -1054,7 +1053,6 @@ out_free:
 		return 0;
 	}
 
-	rte_prefetch0(&((&txq->q)->sdesc->mbuf->pool));
 	pi = (struct port_info *)txq->eth_dev->data->dev_private;
 	adap = pi->adapter;
 
@@ -1070,6 +1068,7 @@ out_free:
 				txq->stats.mapping_err++;
 				goto out_free;
 			}
+			rte_prefetch0((volatile void *)addr);
 			return tx_do_packet_coalesce(txq, mbuf, cflits, adap,
 						     pi, addr);
 		} else {
@@ -1454,7 +1453,8 @@ static int process_responses(struct sge_rspq *q, int budget,
 			unsigned int params;
 			u32 val;
 
-			__refill_fl(q->adapter, &rxq->fl);
+			if (fl_cap(&rxq->fl) - rxq->fl.avail >= 64)
+				__refill_fl(q->adapter, &rxq->fl);
 			params = V_QINTR_TIMER_IDX(X_TIMERREG_UPDATE_CIDX);
 			q->next_intr_params = params;
 			val = V_CIDXINC(cidx_inc) | V_SEINTARM(params);
-- 
2.5.3