From: François Tigeot <ftigeot@wolfpond.org>
Date: Sat, 25 Aug 2012 15:25:26 +0000 (+0200)
Subject: ixgbe: add tso_pullup function
X-Git-Tag: v3.2.0~247
X-Git-Url: https://gitweb.dragonflybsd.org/dragonfly.git/commitdiff_plain/857fbe11cb425f03036d582c4f79ae3bbfae92eb?ds=sidebyside

ixgbe: add tso_pullup function

* This routine rearranges mbuf chains to get more continuous bytes,
  potentially increasing tcp send performance

* Single TCP streams are now able to push slightly more than 4Gb/s
  under the right circumstances

Taken-from: Sepherosa Ziehau's work on the igb(4) driver
---

diff --git a/sys/dev/netif/ixgbe/ixgbe.c b/sys/dev/netif/ixgbe/ixgbe.c
index c07165e5e3..96da6d0590 100644
--- a/sys/dev/netif/ixgbe/ixgbe.c
+++ b/sys/dev/netif/ixgbe/ixgbe.c
@@ -167,6 +167,7 @@ static void	ixgbe_add_rx_process_limit(struct adapter *, const char *,
 		    const char *, int *, int);
 static bool	ixgbe_tx_ctx_setup(struct tx_ring *, struct mbuf *);
 static bool	ixgbe_tso_setup(struct tx_ring *, struct mbuf *, u32 *, u32 *);
+static int	ixgbe_tso_pullup(struct tx_ring *, struct mbuf **);
 static void	ixgbe_set_ivar(struct adapter *, u8, u8, s8);
 static void	ixgbe_configure_ivars(struct adapter *);
 static u8 *	ixgbe_mc_array_itr(struct ixgbe_hw *, u8 **, u32 *);
@@ -1744,6 +1745,13 @@ ixgbe_xmit(struct tx_ring *txr, struct mbuf **m_headp)
 
 	m_head = *m_headp;
 
+	if (m_head->m_pkthdr.csum_flags & CSUM_TSO) {
+		error = ixgbe_tso_pullup(txr, m_headp);
+		if (error)
+			return error;
+		m_head = *m_headp;
+	}
+
 	/* Basic descriptor defines */
         cmd_type_len = (IXGBE_ADVTXD_DTYP_DATA |
 	    IXGBE_ADVTXD_DCMD_IFCS | IXGBE_ADVTXD_DCMD_DEXT);
@@ -5797,3 +5805,33 @@ ixgbe_set_thermal_test(SYSCTL_HANDLER_ARGS)
 
 	return (0);
 }
+
+/* rearrange mbuf chain to get contiguous bytes */
+static int
+ixgbe_tso_pullup(struct tx_ring *txr, struct mbuf **mp)
+{
+	int hoff, iphlen, thoff;
+	struct mbuf *m;
+
+	m = *mp;
+	KASSERT(M_WRITABLE(m), ("TSO mbuf not writable"));
+
+	iphlen = m->m_pkthdr.csum_iphlen;
+	thoff = m->m_pkthdr.csum_thlen;
+	hoff = m->m_pkthdr.csum_lhlen;
+
+	KASSERT(iphlen > 0, ("invalid ip hlen"));
+	KASSERT(thoff > 0, ("invalid tcp hlen"));
+	KASSERT(hoff > 0, ("invalid ether hlen"));
+
+	if (__predict_false(m->m_len < hoff + iphlen + thoff)) {
+		m = m_pullup(m, hoff + iphlen + thoff);
+		if (m == NULL) {
+			*mp = NULL;
+			return ENOBUFS;
+		}
+		*mp = m;
+	}
+
+	return 0;
+}