[PATCH] scsi: target: cxgbit: enable Delayed ACK

[PATCH] scsi: target: cxgbit: enable Delayed ACK

[Varun Prakash]

Enable Delayed ACK to reduce the number of TCP ACKs.

Signed-off-by: Varun Prakash <varun@chelsio.com>
---
 drivers/target/iscsi/cxgbit/cxgbit_cm.c     |  8 +++-----
 drivers/target/iscsi/cxgbit/cxgbit_target.c | 28 +++++++++++++++++++++++-----
 2 files changed, 26 insertions(+), 10 deletions(-)

diff --git a/drivers/target/iscsi/cxgbit/cxgbit_cm.c b/drivers/target/iscsi/cxgbit/cxgbit_cm.c
index 518ded2..da31a30 100644
--- a/drivers/target/iscsi/cxgbit/cxgbit_cm.c
+++ b/drivers/target/iscsi/cxgbit/cxgbit_cm.c
@@ -836,11 +836,13 @@ static void cxgbit_set_tcp_window(struct cxgbit_sock *csk, struct port_info *pi)
 	csk->rcv_win = CXGBIT_10G_RCV_WIN;
 	if (scale)
 		csk->rcv_win *= scale;
+	csk->rcv_win = min(csk->rcv_win, RCV_BUFSIZ_M << 10);
 
 #define CXGBIT_10G_SND_WIN (256 * 1024)
 	csk->snd_win = CXGBIT_10G_SND_WIN;
 	if (scale)
 		csk->snd_win *= scale;
+	csk->snd_win = min(csk->snd_win, 512U * 1024);
 
 	pr_debug("%s snd_win %d rcv_win %d\n",
 		 __func__, csk->snd_win, csk->rcv_win);
@@ -1065,7 +1067,7 @@ int cxgbit_rx_data_ack(struct cxgbit_sock *csk)
 	if (!skb)
 		return -1;
 
-	credit_dack = RX_DACK_CHANGE_F | RX_DACK_MODE_V(1) |
+	credit_dack = RX_DACK_CHANGE_F | RX_DACK_MODE_V(3) |
 		      RX_CREDITS_V(csk->rx_credits);
 
 	cxgb_mk_rx_data_ack(skb, len, csk->tid, csk->ctrlq_idx,
@@ -1197,7 +1199,6 @@ cxgbit_pass_accept_rpl(struct cxgbit_sock *csk, struct cpl_pass_accept_req *req)
 	if (tcph->ece && tcph->cwr)
 		opt2 |= CCTRL_ECN_V(1);
 
-	opt2 |= RX_COALESCE_V(3);
 	opt2 |= CONG_CNTRL_V(CONG_ALG_NEWRENO);
 
 	opt2 |= T5_ISS_F;
@@ -1646,9 +1647,6 @@ cxgbit_pass_establish(struct cxgbit_device *cdev, struct sk_buff *skb)
 
 	csk->rcv_nxt = rcv_isn;
 
-	if (csk->rcv_win > (RCV_BUFSIZ_M << 10))
-		csk->rx_credits = (csk->rcv_win - (RCV_BUFSIZ_M << 10));
-
 	csk->snd_wscale = TCPOPT_SND_WSCALE_G(tcp_opt);
 	cxgbit_set_emss(csk, tcp_opt);
 	dst_confirm(csk->dst);
diff --git a/drivers/target/iscsi/cxgbit/cxgbit_target.c b/drivers/target/iscsi/cxgbit/cxgbit_target.c
index 282297f..d314ee1 100644
--- a/drivers/target/iscsi/cxgbit/cxgbit_target.c
+++ b/drivers/target/iscsi/cxgbit/cxgbit_target.c
@@ -189,8 +189,8 @@ cxgbit_tx_data_wr(struct cxgbit_sock *csk, struct sk_buff *skb, u32 dlen,
 	wr_ulp_mode = FW_OFLD_TX_DATA_WR_ULPMODE_V(ULP_MODE_ISCSI) |
 				FW_OFLD_TX_DATA_WR_ULPSUBMODE_V(submode);
 
-	req->tunnel_to_proxy = htonl((wr_ulp_mode) | force |
-		 FW_OFLD_TX_DATA_WR_SHOVE_V(skb_peek(&csk->txq) ? 0 : 1));
+	req->tunnel_to_proxy = htonl(wr_ulp_mode | force |
+				     FW_OFLD_TX_DATA_WR_SHOVE_F);
 }
 
 static void cxgbit_arp_failure_skb_discard(void *handle, struct sk_buff *skb)
@@ -1531,7 +1531,7 @@ static int cxgbit_process_lro_skb(struct cxgbit_sock *csk, struct sk_buff *skb)
 	return ret;
 }
 
-static int cxgbit_rx_lro_skb(struct cxgbit_sock *csk, struct sk_buff *skb)
+static int cxgbit_t5_rx_lro_skb(struct cxgbit_sock *csk, struct sk_buff *skb)
 {
 	struct cxgbit_lro_cb *lro_cb = cxgbit_skb_lro_cb(skb);
 	struct cxgbit_lro_pdu_cb *pdu_cb = cxgbit_skb_lro_pdu_cb(skb, 0);
@@ -1557,6 +1557,24 @@ static int cxgbit_rx_lro_skb(struct cxgbit_sock *csk, struct sk_buff *skb)
 	return ret;
 }
 
+static int cxgbit_rx_lro_skb(struct cxgbit_sock *csk, struct sk_buff *skb)
+{
+	struct cxgbit_lro_cb *lro_cb = cxgbit_skb_lro_cb(skb);
+	int ret;
+
+	ret = cxgbit_process_lro_skb(csk, skb);
+	if (ret)
+		return ret;
+
+	csk->rx_credits += lro_cb->pdu_totallen;
+	if (csk->rx_credits >= csk->rcv_win) {
+		csk->rx_credits = 0;
+		cxgbit_rx_data_ack(csk);
+	}
+
+	return 0;
+}
+
 static int cxgbit_rx_skb(struct cxgbit_sock *csk, struct sk_buff *skb)
 {
 	struct cxgb4_lld_info *lldi = &csk->com.cdev->lldi;
@@ -1564,9 +1582,9 @@ static int cxgbit_rx_skb(struct cxgbit_sock *csk, struct sk_buff *skb)
 
 	if (likely(cxgbit_skcb_flags(skb) & SKCBF_RX_LRO)) {
 		if (is_t5(lldi->adapter_type))
-			ret = cxgbit_rx_lro_skb(csk, skb);
+			ret = cxgbit_t5_rx_lro_skb(csk, skb);
 		else
-			ret = cxgbit_process_lro_skb(csk, skb);
+			ret = cxgbit_rx_lro_skb(csk, skb);
 	}
 
 	__kfree_skb(skb);
-- 
2.0.2

Re: [PATCH] scsi: target: cxgbit: enable Delayed ACK

[Martin K. Petersen]

Varun,

> Enable Delayed ACK to reduce the number of TCP ACKs.

Applied to 5.16/scsi-staging, thanks!

-- 
Martin K. Petersen	Oracle Linux Engineering

Re: [PATCH] scsi: target: cxgbit: enable Delayed ACK

[Martin K. Petersen]

On Wed, 13 Oct 2021 19:55:09 +0530, Varun Prakash wrote:

> Enable Delayed ACK to reduce the number of TCP ACKs.
> 
> 

Applied to 5.16/scsi-queue, thanks!

[1/1] scsi: target: cxgbit: enable Delayed ACK
      https://git.kernel.org/mkp/scsi/c/d1e51ea6bf5f

-- 
Martin K. Petersen	Oracle Linux Engineering