ipv6: Create percpu rt6_info
After the patch
'ipv6: Only create RTF_CACHE routes after encountering pmtu exception',
we need to compensate the performance hit (bouncing dst->__refcnt).
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Julian Anastasov <ja@ssi.bg>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 90c8eaa..1a1122a 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -165,11 +165,18 @@
}
}
+static u32 *rt6_pcpu_cow_metrics(struct rt6_info *rt)
+{
+ return dst_metrics_write_ptr(rt->dst.from);
+}
+
static u32 *ipv6_cow_metrics(struct dst_entry *dst, unsigned long old)
{
struct rt6_info *rt = (struct rt6_info *)dst;
- if (rt->rt6i_flags & RTF_CACHE)
+ if (rt->rt6i_flags & RTF_PCPU)
+ return rt6_pcpu_cow_metrics(rt);
+ else if (rt->rt6i_flags & RTF_CACHE)
return NULL;
else
return dst_cow_metrics_generic(dst, old);
@@ -309,10 +316,10 @@
#endif
/* allocate dst with ip6_dst_ops */
-static inline struct rt6_info *ip6_dst_alloc(struct net *net,
- struct net_device *dev,
- int flags,
- struct fib6_table *table)
+static struct rt6_info *__ip6_dst_alloc(struct net *net,
+ struct net_device *dev,
+ int flags,
+ struct fib6_table *table)
{
struct rt6_info *rt = dst_alloc(&net->ipv6.ip6_dst_ops, dev,
0, DST_OBSOLETE_FORCE_CHK, flags);
@@ -327,6 +334,34 @@
return rt;
}
+static struct rt6_info *ip6_dst_alloc(struct net *net,
+ struct net_device *dev,
+ int flags,
+ struct fib6_table *table)
+{
+ struct rt6_info *rt = __ip6_dst_alloc(net, dev, flags, table);
+
+ if (rt) {
+ rt->rt6i_pcpu = alloc_percpu_gfp(struct rt6_info *, GFP_ATOMIC);
+ if (rt->rt6i_pcpu) {
+ int cpu;
+
+ for_each_possible_cpu(cpu) {
+ struct rt6_info **p;
+
+ p = per_cpu_ptr(rt->rt6i_pcpu, cpu);
+ /* no one shares rt */
+ *p = NULL;
+ }
+ } else {
+ dst_destroy((struct dst_entry *)rt);
+ return NULL;
+ }
+ }
+
+ return rt;
+}
+
static void ip6_dst_destroy(struct dst_entry *dst)
{
struct rt6_info *rt = (struct rt6_info *)dst;
@@ -335,6 +370,9 @@
dst_destroy_metrics_generic(dst);
+ if (rt->rt6i_pcpu)
+ free_percpu(rt->rt6i_pcpu);
+
rt6_uncached_list_del(rt);
idev = rt->rt6i_idev;
@@ -912,11 +950,11 @@
* Clone the route.
*/
- if (ort->rt6i_flags & RTF_CACHE)
+ if (ort->rt6i_flags & (RTF_CACHE | RTF_PCPU))
ort = (struct rt6_info *)ort->dst.from;
- rt = ip6_dst_alloc(dev_net(ort->dst.dev), ort->dst.dev,
- 0, ort->rt6i_table);
+ rt = __ip6_dst_alloc(dev_net(ort->dst.dev), ort->dst.dev,
+ 0, ort->rt6i_table);
if (!rt)
return NULL;
@@ -943,6 +981,54 @@
return rt;
}
+static struct rt6_info *ip6_rt_pcpu_alloc(struct rt6_info *rt)
+{
+ struct rt6_info *pcpu_rt;
+
+ pcpu_rt = __ip6_dst_alloc(dev_net(rt->dst.dev),
+ rt->dst.dev, rt->dst.flags,
+ rt->rt6i_table);
+
+ if (!pcpu_rt)
+ return NULL;
+ ip6_rt_copy_init(pcpu_rt, rt);
+ pcpu_rt->rt6i_protocol = rt->rt6i_protocol;
+ pcpu_rt->rt6i_flags |= RTF_PCPU;
+ return pcpu_rt;
+}
+
+/* It should be called with read_lock_bh(&tb6_lock) acquired */
+static struct rt6_info *rt6_get_pcpu_route(struct rt6_info *rt)
+{
+ struct rt6_info *pcpu_rt, *prev, **p;
+
+ p = this_cpu_ptr(rt->rt6i_pcpu);
+ pcpu_rt = *p;
+
+ if (pcpu_rt)
+ goto done;
+
+ pcpu_rt = ip6_rt_pcpu_alloc(rt);
+ if (!pcpu_rt) {
+ struct net *net = dev_net(rt->dst.dev);
+
+ pcpu_rt = net->ipv6.ip6_null_entry;
+ goto done;
+ }
+
+ prev = cmpxchg(p, NULL, pcpu_rt);
+ if (prev) {
+ /* If someone did it before us, return prev instead */
+ dst_destroy(&pcpu_rt->dst);
+ pcpu_rt = prev;
+ }
+
+done:
+ dst_hold(&pcpu_rt->dst);
+ rt6_dst_from_metrics_check(pcpu_rt);
+ return pcpu_rt;
+}
+
static struct rt6_info *ip6_pol_route(struct net *net, struct fib6_table *table, int oif,
struct flowi6 *fl6, int flags)
{
@@ -975,11 +1061,13 @@
}
}
- dst_use(&rt->dst, jiffies);
- read_unlock_bh(&table->tb6_lock);
if (rt == net->ipv6.ip6_null_entry || (rt->rt6i_flags & RTF_CACHE)) {
- goto done;
+ dst_use(&rt->dst, jiffies);
+ read_unlock_bh(&table->tb6_lock);
+
+ rt6_dst_from_metrics_check(rt);
+ return rt;
} else if (unlikely((fl6->flowi6_flags & FLOWI_FLAG_KNOWN_NH) &&
!(rt->rt6i_flags & RTF_GATEWAY))) {
/* Create a RTF_CACHE clone which will not be
@@ -990,6 +1078,9 @@
struct rt6_info *uncached_rt;
+ dst_use(&rt->dst, jiffies);
+ read_unlock_bh(&table->tb6_lock);
+
uncached_rt = ip6_rt_cache_alloc(rt, &fl6->daddr, NULL);
dst_release(&rt->dst);
@@ -997,13 +1088,22 @@
rt6_uncached_list_add(uncached_rt);
else
uncached_rt = net->ipv6.ip6_null_entry;
+
dst_hold(&uncached_rt->dst);
return uncached_rt;
- }
-done:
- rt6_dst_from_metrics_check(rt);
- return rt;
+ } else {
+ /* Get a percpu copy */
+
+ struct rt6_info *pcpu_rt;
+
+ rt->dst.lastuse = jiffies;
+ rt->dst.__use++;
+ pcpu_rt = rt6_get_pcpu_route(rt);
+ read_unlock_bh(&table->tb6_lock);
+
+ return pcpu_rt;
+ }
}
static struct rt6_info *ip6_pol_route_input(struct net *net, struct fib6_table *table,
@@ -1147,7 +1247,7 @@
rt6_dst_from_metrics_check(rt);
- if (unlikely(dst->flags & DST_NOCACHE))
+ if ((rt->rt6i_flags & RTF_PCPU) || unlikely(dst->flags & DST_NOCACHE))
return rt6_dst_from_check(rt, cookie);
else
return rt6_check(rt, cookie);