This patch checks device locality on every ip packet xmit.
In multipath configuration tcp connection to route association is done at
session startup time. The tcp session process is migrated to different nodes
after this association. This would mean a remote NIC is chosen for xmit,
although a local NIC could be available. Following patch checks if a
local NIC is available for the desitnation, and recalculates routes if so.
his leads to remote NIC transfer in some tcp work load such as AB.
Downside: adds a bitmap to struct rtable. But only if
CONFIG_IP_ROUTE_MULTIPATH_NODE is enabled.
Comments, suggestions welcome.
Signed-off by: Pravin B. Shelar <[email protected]>
Signed-off by: Ravikiran Thirumalai <[email protected]>
Signed-off by: Shai Fultheim <[email protected]>
Index: linux-2.6.16/include/net/route.h
===================================================================
--- linux-2.6.16.orig/include/net/route.h 2006-03-19 21:53:29.000000000 -0800
+++ linux-2.6.16/include/net/route.h 2006-03-20 14:52:24.000000000 -0800
@@ -75,6 +75,13 @@ struct rtable
/* Miscellaneous cached information */
__u32 rt_spec_dst; /* RFC1122 specific destination */
struct inet_peer *peer; /* long-living peer info */
+#ifdef CONFIG_IP_ROUTE_MULTIPATH_NODE
+ /* bitmap bit is set if current node has a local multi-path device for
+ * this route.
+ */
+ DECLARE_BITMAP (mp_if_bitmap, MAX_NUMNODES);
+#endif
+
};
struct ip_rt_acct
@@ -201,4 +208,21 @@ static inline struct inet_peer *rt_get_p
extern ctl_table ipv4_route_table[];
+#ifdef CONFIG_IP_ROUTE_MULTIPATH_NODE
+
+#include <linux/ip_mp_alg.h>
+
+static inline int dst_dev_node_check(struct rtable *rt)
+{
+ int cnode = numa_node_id();
+ if (unlikely(netdev_node(rt->u.dst.dev) != cnode)) {
+ if (test_bit(cnode, rt->mp_if_bitmap))
+ return 1;
+ }
+ return 0;
+}
+#else
+#define dst_dev_node_check(rt) 0
+#endif
+
#endif /* _ROUTE_H */
Index: linux-2.6.16/net/ipv4/ip_output.c
===================================================================
--- linux-2.6.16.orig/net/ipv4/ip_output.c 2006-03-19 21:53:29.000000000 -0800
+++ linux-2.6.16/net/ipv4/ip_output.c 2006-03-20 14:52:24.000000000 -0800
@@ -309,7 +309,7 @@ int ip_queue_xmit(struct sk_buff *skb, i
/* Make sure we can route this packet. */
rt = (struct rtable *)__sk_dst_check(sk, 0);
- if (rt == NULL) {
+ if ((rt == NULL ) || dst_dev_node_check(rt)) {
u32 daddr;
/* Use correct destination address if we have options. */
Index: linux-2.6.16/net/ipv4/route.c
===================================================================
--- linux-2.6.16.orig/net/ipv4/route.c 2006-03-19 21:53:29.000000000 -0800
+++ linux-2.6.16/net/ipv4/route.c 2006-03-20 14:52:24.000000000 -0800
@@ -2313,6 +2313,22 @@ static inline int ip_mkroute_output(stru
if (res->fi && res->fi->fib_nhs > 1) {
unsigned char hopcount = res->fi->fib_nhs;
+#ifdef CONFIG_IP_ROUTE_MULTIPATH_NODE
+ DECLARE_BITMAP (mp_if_bitmap, MAX_NUMNODES);
+ bitmap_zero(mp_if_bitmap, MAX_NUMNODES);
+ /* Calculating device bitmap for this multipath route */
+ if (res->fi->fib_mp_alg == IP_MP_ALG_DRR) {
+ for (hop = 0; hop < hopcount; hop++) {
+ struct net_device *dev2nexthop;
+
+ res->nh_sel = hop;
+ dev2nexthop = FIB_RES_DEV(*res);
+ dev_hold(dev2nexthop);
+ set_bit(netdev_node(dev2nexthop), mp_if_bitmap);
+ dev_put(dev2nexthop);
+ }
+ }
+#endif
for (hop = 0; hop < hopcount; hop++) {
struct net_device *dev2nexthop;
@@ -2343,6 +2359,10 @@ static inline int ip_mkroute_output(stru
FIB_RES_NETMASK(*res),
res->prefixlen,
&FIB_RES_NH(*res));
+
+#ifdef CONFIG_IP_ROUTE_MULTIPATH_NODE
+ bitmap_copy(rth->mp_if_bitmap, mp_if_bitmap, MAX_NUMNODES);
+#endif
cleanup:
/* release work reference to output device */
dev_put(dev2nexthop);
-
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