MFC r271946 and r272595:

Improve transmit sending offload, TSO, algorithm in general. This
change allows all HCAs from Mellanox Technologies to function properly
when TSO is enabled. See r271946 and r272595 for more details about
this commit.

Sponsored by:	Mellanox Technologies

1 files changed, 80 insertions, 6 deletions

diff --git a/sys/net/if.c b/sys/net/if.c
index a658384..2e5d0ab 100644
--- a/sys/net/if.c
+++ b/sys/net/if.c
@@ -583,6 +583,57 @@ if_attach(struct ifnet *ifp)
 	if_attach_internal(ifp, 0);
 }
 
+/*
+ * Compute the least common TSO limit.
+ */
+void
+if_hw_tsomax_common(struct ifnet *ifp, struct ifnet_hw_tsomax *pmax)
+{
+	/*
+	 * 1) If there is no limit currently, take the limit from
+	 * the network adapter.
+	 *
+	 * 2) If the network adapter has a limit below the current
+	 * limit, apply it.
+	 */
+	if (pmax->tsomaxbytes == 0 || (ifp->if_hw_tsomax != 0 &&
+	    ifp->if_hw_tsomax < pmax->tsomaxbytes)) {
+		pmax->tsomaxbytes = ifp->if_hw_tsomax;
+	}
+	if (pmax->tsomaxsegcount == 0 || (ifp->if_hw_tsomaxsegcount != 0 &&
+	    ifp->if_hw_tsomaxsegcount < pmax->tsomaxsegcount)) {
+		pmax->tsomaxsegcount = ifp->if_hw_tsomaxsegcount;
+	}
+	if (pmax->tsomaxsegsize == 0 || (ifp->if_hw_tsomaxsegsize != 0 &&
+	    ifp->if_hw_tsomaxsegsize < pmax->tsomaxsegsize)) {
+		pmax->tsomaxsegsize = ifp->if_hw_tsomaxsegsize;
+	}
+}
+
+/*
+ * Update TSO limit of a network adapter.
+ *
+ * Returns zero if no change. Else non-zero.
+ */
+int
+if_hw_tsomax_update(struct ifnet *ifp, struct ifnet_hw_tsomax *pmax)
+{
+	int retval = 0;
+	if (ifp->if_hw_tsomax != pmax->tsomaxbytes) {
+		ifp->if_hw_tsomax = pmax->tsomaxbytes;
+		retval++;
+	}
+	if (ifp->if_hw_tsomaxsegsize != pmax->tsomaxsegsize) {
+		ifp->if_hw_tsomaxsegsize = pmax->tsomaxsegsize;
+		retval++;
+	}
+	if (ifp->if_hw_tsomaxsegcount != pmax->tsomaxsegcount) {
+		ifp->if_hw_tsomaxsegcount = pmax->tsomaxsegcount;
+		retval++;
+	}
+	return (retval);
+}
+
 static void
 if_attach_internal(struct ifnet *ifp, int vmove)
 {
@@ -657,13 +708,36 @@ if_attach_internal(struct ifnet *ifp, int vmove)
 		ifp->if_broadcastaddr = NULL;
 
 #if defined(INET) || defined(INET6)
-		/* Initialize to max value. */
-		if (ifp->if_hw_tsomax == 0)
-			ifp->if_hw_tsomax = min(IP_MAXPACKET, 32 * MCLBYTES -
+		/* Use defaults for TSO, if nothing is set */
+		if (ifp->if_hw_tsomax == 0 &&
+		    ifp->if_hw_tsomaxsegcount == 0 &&
+		    ifp->if_hw_tsomaxsegsize == 0) {
+			/*
+			 * The TSO defaults needs to be such that an
+			 * NFS mbuf list of 35 mbufs totalling just
+			 * below 64K works and that a chain of mbufs
+			 * can be defragged into at most 32 segments:
+			 */
+			ifp->if_hw_tsomax = min(IP_MAXPACKET, (32 * MCLBYTES) -
 			    (ETHER_HDR_LEN + ETHER_VLAN_ENCAP_LEN));
-		KASSERT(ifp->if_hw_tsomax <= IP_MAXPACKET &&
-		    ifp->if_hw_tsomax >= IP_MAXPACKET / 8,
-		    ("%s: tsomax outside of range", __func__));
+			ifp->if_hw_tsomaxsegcount = 35;
+			ifp->if_hw_tsomaxsegsize = 2048;	/* 2K */
+
+			/* XXX some drivers set IFCAP_TSO after ethernet attach */
+			if (ifp->if_capabilities & IFCAP_TSO) {
+				if_printf(ifp, "Using defaults for TSO: %u/%u/%u\n",
+				    ifp->if_hw_tsomax,
+				    ifp->if_hw_tsomaxsegcount,
+				    ifp->if_hw_tsomaxsegsize);
+			}
+		}
+		/*
+		 * If the "if_hw_tsomax" limit is set, check if it is
+		 * too small:
+		 */
+		KASSERT(ifp->if_hw_tsomax == 0 ||
+		    ifp->if_hw_tsomax >= (IP_MAXPACKET / 8),
+		    ("%s: if_hw_tsomax is outside of range", __func__));
 #endif
 	}
 #ifdef VIMAGE