From d52d3997f843ffefaa8d8462790ffcaca6c74192 Mon Sep 17 00:00:00 2001 From: Martin KaFai Lau Date: Fri, 22 May 2015 20:56:06 -0700 Subject: [PATCH] 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 Cc: Hannes Frederic Sowa Cc: Steffen Klassert Cc: Julian Anastasov Signed-off-by: David S. Miller --- include/net/ip6_fib.h | 3 +- include/uapi/linux/ipv6_route.h | 1 + net/ipv6/ip6_fib.c | 24 +++++- net/ipv6/route.c | 132 ++++++++++++++++++++++++++++---- 4 files changed, 142 insertions(+), 18 deletions(-) diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h index cc8f03c10c43..3b76849c190f 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 2be7bd174751..f6598d1c886e 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 83341b3a248d..55d19861ab20 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 90c8eaa24565..1a1122a6bbf5 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 +981,54 @@ 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; +} + +/* 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 @@ 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 +1078,9 @@ 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 +1088,22 @@ 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 +1247,7 @@ 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);