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 <ka...@fb.com>
Cc: Hannes Frederic Sowa <han...@stressinduktion.org>
Cc: Steffen Klassert <steffen.klass...@secunet.com>
Cc: Julian Anastasov <j...@ssi.bg>
---
include/net/ip6_fib.h | 3 +-
include/uapi/linux/ipv6_route.h | 1 +
net/ipv6/ip6_fib.c | 24 ++++++-
net/ipv6/route.c | 134 +++++++++++++++++++++++++++++++++++-----
4 files changed, 144 insertions(+), 18 deletions(-)
diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
index cc8f03c..3b76849 100644
--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h
@@ -124,6 +124,7 @@ struct rt6_info {
struct uncached_list *rt6i_uncached_list;
struct inet6_dev *rt6i_idev;
+ struct rt6_info * __percpu *rt6i_pcpu;
u32 rt6i_metric;
u32 rt6i_pmtu;
@@ -164,7 +165,7 @@ static inline void rt6_update_expires(struct rt6_info *rt0,
int timeout)
static inline u32 rt6_get_cookie(const struct rt6_info *rt)
{
- if (unlikely(rt->dst.flags & DST_NOCACHE))
+ if (rt->rt6i_flags & RTF_PCPU || unlikely(rt->dst.flags & DST_NOCACHE))
rt = (struct rt6_info *)(rt->dst.from);
return rt->rt6i_node ? rt->rt6i_node->fn_sernum : 0;
diff --git a/include/uapi/linux/ipv6_route.h b/include/uapi/linux/ipv6_route.h
index 2be7bd1..f6598d1 100644
--- a/include/uapi/linux/ipv6_route.h
+++ b/include/uapi/linux/ipv6_route.h
@@ -34,6 +34,7 @@
#define RTF_PREF(pref) ((pref) << 27)
#define RTF_PREF_MASK 0x18000000
+#define RTF_PCPU 0x40000000
#define RTF_LOCAL 0x80000000
diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index 7d66490..bab2490 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -154,10 +154,32 @@ static void node_free(struct fib6_node *fn)
kmem_cache_free(fib6_node_kmem, fn);
}
+static void rt6_free_pcpu(struct rt6_info *non_pcpu_rt)
+{
+ int cpu;
+
+ if (!non_pcpu_rt->rt6i_pcpu)
+ return;
+
+ for_each_possible_cpu(cpu) {
+ struct rt6_info **ppcpu_rt;
+ struct rt6_info *pcpu_rt;
+
+ ppcpu_rt = per_cpu_ptr(non_pcpu_rt->rt6i_pcpu, cpu);
+ pcpu_rt = *ppcpu_rt;
+ if (pcpu_rt) {
+ dst_free(&pcpu_rt->dst);
+ *ppcpu_rt = NULL;
+ }
+ }
+}
+
static void rt6_release(struct rt6_info *rt)
{
- if (atomic_dec_and_test(&rt->rt6i_ref))
+ if (atomic_dec_and_test(&rt->rt6i_ref)) {
+ rt6_free_pcpu(rt);
dst_free(&rt->dst);
+ }
}
static void fib6_link_table(struct net *net, struct fib6_table *tb)
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index e8655d0..3d741b2 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -165,11 +165,18 @@ static void rt6_uncached_list_flush_dev(struct net *net,
struct net_device *dev)
}
}
+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 @@ static const struct rt6_info ip6_blk_hole_entry_template
= {
#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 @@ static inline struct rt6_info *ip6_dst_alloc(struct net
*net,
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 @@ static void ip6_dst_destroy(struct dst_entry *dst)
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 @@ static struct rt6_info *ip6_rt_cache_alloc(struct
rt6_info *ort,
* 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 +981,56 @@ static struct rt6_info *ip6_rt_cache_alloc(struct rt6_info
*ort,
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;
+}
+
+static struct rt6_info *rt6_get_pcpu_route(struct rt6_info *rt)
+{
+ struct rt6_info *pcpu_rt, *orig, *prev, **p;
+ struct net *net = dev_net(rt->dst.dev);
+
+ /* It is under read_lock_bh */
+ p = this_cpu_ptr(rt->rt6i_pcpu);
+ orig = *p;
+
+ if (orig) {
+ dst_hold(&orig->dst);
+ rt6_dst_from_metrics_check(orig);
+ return orig;
+ }
+
+ pcpu_rt = ip6_rt_pcpu_alloc(rt);
+ if (!pcpu_rt) {
+ rt = net->ipv6.ip6_null_entry;
+ dst_hold(&rt->dst);
+ return rt;
+ }
+ dst_hold(&pcpu_rt->dst);
+
+ prev = cmpxchg(p, orig, pcpu_rt);
+ if (prev)
+ /* orig must be NULL, so no need to consider freeing prev.
+ * If someone did it before us, put pcpu_rt in uncached_list
+ * before returning it.
+ */
+ rt6_uncached_list_add(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 +1063,13 @@ redo_rt6_select:
}
}
- 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 +1080,9 @@ redo_rt6_select:
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 +1090,22 @@ redo_rt6_select:
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 +1249,7 @@ static struct dst_entry *ip6_dst_check(struct dst_entry
*dst, u32 cookie)
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);
--
1.8.1
--
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