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net dst: use a percpu_counter to track entries 

struct dst_ops tracks number of allocated dst in an atomic_t field,
subject to high cache line contention in stress workload.

Switch to a percpu_counter, to reduce number of time we need to dirty a
central location. Place it on a separate cache line to avoid dirtying
read only fields.

Stress test :

(Sending 160.000.000 UDP frames,
IP route cache disabled, dual E5540 @2.53GHz,
32bit kernel, FIB_TRIE, SLUB/NUMA)

Before:

real    0m51.179s
user    0m15.329s
sys     10m15.942s

After:

real	0m45.570s
user	0m15.525s
sys	9m56.669s

With a small reordering of struct neighbour fields, subject of a
following patch, (to separate refcnt from other read mostly fields)

real	0m41.841s
user	0m15.261s
sys	8m45.949s

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2010-10-08 06:37:34 +00:00 committed by David S. Miller
parent 0ed8ddf404
commit fc66f95c68
8 changed files with 100 additions and 35 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

37
include/net/dst_ops.h
View File

@ -1,6 +1,7 @@
#ifndef _NET_DST_OPS_H
#define _NET_DST_OPS_H
#include <linux/types.h>
#include <linux/percpu_counter.h>
struct dst_entry;
struct kmem_cachep;
@ -22,7 +23,41 @@ struct dst_ops {
void (*update_pmtu)(struct dst_entry *dst, u32 mtu);
int (*local_out)(struct sk_buff *skb);
atomic_t entries;
struct kmem_cache *kmem_cachep;
struct percpu_counter pcpuc_entries ____cacheline_aligned_in_smp;
};
static inline int dst_entries_get_fast(struct dst_ops *dst)
{
return percpu_counter_read_positive(&dst->pcpuc_entries);
}
static inline int dst_entries_get_slow(struct dst_ops *dst)
{
int res;
local_bh_disable();
res = percpu_counter_sum_positive(&dst->pcpuc_entries);
local_bh_enable();
return res;
}
static inline void dst_entries_add(struct dst_ops *dst, int val)
{
local_bh_disable();
percpu_counter_add(&dst->pcpuc_entries, val);
local_bh_enable();
}
static inline int dst_entries_init(struct dst_ops *dst)
{
return percpu_counter_init(&dst->pcpuc_entries, 0);
}
static inline void dst_entries_destroy(struct dst_ops *dst)
{
percpu_counter_destroy(&dst->pcpuc_entries);
}
#endif

11
net/bridge/br_netfilter.c
View File

@ -106,7 +106,6 @@ static struct dst_ops fake_dst_ops = {
.family = AF_INET,
.protocol = cpu_to_be16(ETH_P_IP),
.update_pmtu = fake_update_pmtu,
.entries = ATOMIC_INIT(0),
};
/*
@ -1003,15 +1002,22 @@ int __init br_netfilter_init(void)
{
int ret;
ret = nf_register_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
ret = dst_entries_init(&fake_dst_ops);
if (ret < 0)
return ret;
ret = nf_register_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
if (ret < 0) {
dst_entries_destroy(&fake_dst_ops);
return ret;
}
#ifdef CONFIG_SYSCTL
brnf_sysctl_header = register_sysctl_paths(brnf_path, brnf_table);
if (brnf_sysctl_header == NULL) {
printk(KERN_WARNING
"br_netfilter: can't register to sysctl.\n");
nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
dst_entries_destroy(&fake_dst_ops);
return -ENOMEM;
}
#endif
@ -1025,4 +1031,5 @@ void br_netfilter_fini(void)
#ifdef CONFIG_SYSCTL
unregister_sysctl_table(brnf_sysctl_header);
#endif
dst_entries_destroy(&fake_dst_ops);
}

6
net/core/dst.c
View File

@ -168,7 +168,7 @@ void *dst_alloc(struct dst_ops *ops)
{
struct dst_entry *dst;
if (ops->gc && atomic_read(&ops->entries) > ops->gc_thresh) {
if (ops->gc && dst_entries_get_fast(ops) > ops->gc_thresh) {
if (ops->gc(ops))
return NULL;
}
@ -183,7 +183,7 @@ void *dst_alloc(struct dst_ops *ops)
#if RT_CACHE_DEBUG >= 2
atomic_inc(&dst_total);
#endif
atomic_inc(&ops->entries);
dst_entries_add(ops, 1);
return dst;
}
EXPORT_SYMBOL(dst_alloc);
@ -236,7 +236,7 @@ again:
neigh_release(neigh);
}
atomic_dec(&dst->ops->entries);
dst_entries_add(dst->ops, -1);
if (dst->ops->destroy)
dst->ops->destroy(dst);

3
net/decnet/dn_route.c
View File

@ -132,7 +132,6 @@ static struct dst_ops dn_dst_ops = {
.negative_advice = dn_dst_negative_advice,
.link_failure = dn_dst_link_failure,
.update_pmtu = dn_dst_update_pmtu,
.entries = ATOMIC_INIT(0),
};
static __inline__ unsigned dn_hash(__le16 src, __le16 dst)
@ -1758,6 +1757,7 @@ void __init dn_route_init(void)
dn_dst_ops.kmem_cachep =
kmem_cache_create("dn_dst_cache", sizeof(struct dn_route), 0,
SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
dst_entries_init(&dn_dst_ops);
setup_timer(&dn_route_timer, dn_dst_check_expire, 0);
dn_route_timer.expires = jiffies + decnet_dst_gc_interval * HZ;
add_timer(&dn_route_timer);
@ -1816,5 +1816,6 @@ void __exit dn_route_cleanup(void)
dn_run_flush(0);
proc_net_remove(&init_net, "decnet_cache");
dst_entries_destroy(&dn_dst_ops);
}

36
net/ipv4/route.c
View File

@ -159,7 +159,6 @@ static struct dst_ops ipv4_dst_ops = {
.link_failure = ipv4_link_failure,
.update_pmtu = ip_rt_update_pmtu,
.local_out = __ip_local_out,
.entries = ATOMIC_INIT(0),
};
#define ECN_OR_COST(class) TC_PRIO_##class
@ -466,7 +465,7 @@ static int rt_cpu_seq_show(struct seq_file *seq, void *v)
seq_printf(seq,"%08x %08x %08x %08x %08x %08x %08x %08x "
" %08x %08x %08x %08x %08x %08x %08x %08x %08x \n",
atomic_read(&ipv4_dst_ops.entries),
dst_entries_get_slow(&ipv4_dst_ops),
st->in_hit,
st->in_slow_tot,
st->in_slow_mc,
@ -945,6 +944,7 @@ static int rt_garbage_collect(struct dst_ops *ops)
struct rtable *rth, **rthp;
unsigned long now = jiffies;
int goal;
int entries = dst_entries_get_fast(&ipv4_dst_ops);
/*
* Garbage collection is pretty expensive,
@ -954,28 +954,28 @@ static int rt_garbage_collect(struct dst_ops *ops)
RT_CACHE_STAT_INC(gc_total);
if (now - last_gc < ip_rt_gc_min_interval &&
atomic_read(&ipv4_dst_ops.entries) < ip_rt_max_size) {
entries < ip_rt_max_size) {
RT_CACHE_STAT_INC(gc_ignored);
goto out;
}
entries = dst_entries_get_slow(&ipv4_dst_ops);
/* Calculate number of entries, which we want to expire now. */
goal = atomic_read(&ipv4_dst_ops.entries) -
(ip_rt_gc_elasticity << rt_hash_log);
goal = entries - (ip_rt_gc_elasticity << rt_hash_log);
if (goal <= 0) {
if (equilibrium < ipv4_dst_ops.gc_thresh)
equilibrium = ipv4_dst_ops.gc_thresh;
goal = atomic_read(&ipv4_dst_ops.entries) - equilibrium;
goal = entries - equilibrium;
if (goal > 0) {
equilibrium += min_t(unsigned int, goal >> 1, rt_hash_mask + 1);
goal = atomic_read(&ipv4_dst_ops.entries) - equilibrium;
goal = entries - equilibrium;
}
} else {
/* We are in dangerous area. Try to reduce cache really
* aggressively.
*/
goal = max_t(unsigned int, goal >> 1, rt_hash_mask + 1);
equilibrium = atomic_read(&ipv4_dst_ops.entries) - goal;
equilibrium = entries - goal;
}
if (now - last_gc >= ip_rt_gc_min_interval)
@ -1032,14 +1032,16 @@ static int rt_garbage_collect(struct dst_ops *ops)
expire >>= 1;
#if RT_CACHE_DEBUG >= 2
printk(KERN_DEBUG "expire>> %u %d %d %d\n", expire,
atomic_read(&ipv4_dst_ops.entries), goal, i);
dst_entries_get_fast(&ipv4_dst_ops), goal, i);
#endif
if (atomic_read(&ipv4_dst_ops.entries) < ip_rt_max_size)
if (dst_entries_get_fast(&ipv4_dst_ops) < ip_rt_max_size)
goto out;
} while (!in_softirq() && time_before_eq(jiffies, now));
if (atomic_read(&ipv4_dst_ops.entries) < ip_rt_max_size)
if (dst_entries_get_fast(&ipv4_dst_ops) < ip_rt_max_size)
goto out;
if (dst_entries_get_slow(&ipv4_dst_ops) < ip_rt_max_size)
goto out;
if (net_ratelimit())
printk(KERN_WARNING "dst cache overflow\n");
@ -1049,11 +1051,12 @@ static int rt_garbage_collect(struct dst_ops *ops)
work_done:
expire += ip_rt_gc_min_interval;
if (expire > ip_rt_gc_timeout ||
atomic_read(&ipv4_dst_ops.entries) < ipv4_dst_ops.gc_thresh)
dst_entries_get_fast(&ipv4_dst_ops) < ipv4_dst_ops.gc_thresh ||
dst_entries_get_slow(&ipv4_dst_ops) < ipv4_dst_ops.gc_thresh)
expire = ip_rt_gc_timeout;
#if RT_CACHE_DEBUG >= 2
printk(KERN_DEBUG "expire++ %u %d %d %d\n", expire,
atomic_read(&ipv4_dst_ops.entries), goal, rover);
dst_entries_get_fast(&ipv4_dst_ops), goal, rover);
#endif
out: return 0;
}
@ -2717,7 +2720,6 @@ static struct dst_ops ipv4_dst_blackhole_ops = {
.destroy = ipv4_dst_destroy,
.check = ipv4_blackhole_dst_check,
.update_pmtu = ipv4_rt_blackhole_update_pmtu,
.entries = ATOMIC_INIT(0),
};
@ -3287,6 +3289,12 @@ int __init ip_rt_init(void)
ipv4_dst_blackhole_ops.kmem_cachep = ipv4_dst_ops.kmem_cachep;
if (dst_entries_init(&ipv4_dst_ops) < 0)
panic("IP: failed to allocate ipv4_dst_ops counter\n");
if (dst_entries_init(&ipv4_dst_blackhole_ops) < 0)
panic("IP: failed to allocate ipv4_dst_blackhole_ops counter\n");
rt_hash_table = (struct rt_hash_bucket *)
alloc_large_system_hash("IP route cache",
sizeof(struct rt_hash_bucket),

4
net/ipv4/xfrm4_policy.c
View File

@ -174,7 +174,7 @@ static inline int xfrm4_garbage_collect(struct dst_ops *ops)
struct net *net = container_of(ops, struct net, xfrm.xfrm4_dst_ops);
xfrm4_policy_afinfo.garbage_collect(net);
return (atomic_read(&ops->entries) > ops->gc_thresh * 2);
return (dst_entries_get_slow(ops) > ops->gc_thresh * 2);
}
static void xfrm4_update_pmtu(struct dst_entry *dst, u32 mtu)
@ -232,7 +232,6 @@ static struct dst_ops xfrm4_dst_ops = {
.ifdown = xfrm4_dst_ifdown,
.local_out = __ip_local_out,
.gc_thresh = 1024,
.entries = ATOMIC_INIT(0),
};
static struct xfrm_policy_afinfo xfrm4_policy_afinfo = {
@ -288,6 +287,7 @@ void __init xfrm4_init(int rt_max_size)
* and start cleaning when were 1/2 full
*/
xfrm4_dst_ops.gc_thresh = rt_max_size/2;
dst_entries_init(&xfrm4_dst_ops);
xfrm4_state_init();
xfrm4_policy_init();

28
net/ipv6/route.c
View File

@ -109,7 +109,6 @@ static struct dst_ops ip6_dst_ops_template = {
.link_failure = ip6_link_failure,
.update_pmtu = ip6_rt_update_pmtu,
.local_out = __ip6_local_out,
.entries = ATOMIC_INIT(0),
};
static void ip6_rt_blackhole_update_pmtu(struct dst_entry *dst, u32 mtu)
@ -122,7 +121,6 @@ static struct dst_ops ip6_dst_blackhole_ops = {
.destroy = ip6_dst_destroy,
.check = ip6_dst_check,
.update_pmtu = ip6_rt_blackhole_update_pmtu,
.entries = ATOMIC_INIT(0),
};
static struct rt6_info ip6_null_entry_template = {
@ -1058,19 +1056,22 @@ static int ip6_dst_gc(struct dst_ops *ops)
int rt_elasticity = net->ipv6.sysctl.ip6_rt_gc_elasticity;
int rt_gc_timeout = net->ipv6.sysctl.ip6_rt_gc_timeout;
unsigned long rt_last_gc = net->ipv6.ip6_rt_last_gc;
int entries;
entries = dst_entries_get_fast(ops);
if (time_after(rt_last_gc + rt_min_interval, now) &&
atomic_read(&ops->entries) <= rt_max_size)
entries <= rt_max_size)
goto out;
net->ipv6.ip6_rt_gc_expire++;
fib6_run_gc(net->ipv6.ip6_rt_gc_expire, net);
net->ipv6.ip6_rt_last_gc = now;
if (atomic_read(&ops->entries) < ops->gc_thresh)
entries = dst_entries_get_slow(ops);
if (entries < ops->gc_thresh)
net->ipv6.ip6_rt_gc_expire = rt_gc_timeout>>1;
out:
net->ipv6.ip6_rt_gc_expire -= net->ipv6.ip6_rt_gc_expire>>rt_elasticity;
return atomic_read(&ops->entries) > rt_max_size;
return entries > rt_max_size;
}
/* Clean host part of a prefix. Not necessary in radix tree,
@ -2524,7 +2525,7 @@ static int rt6_stats_seq_show(struct seq_file *seq, void *v)
net->ipv6.rt6_stats->fib_rt_alloc,
net->ipv6.rt6_stats->fib_rt_entries,
net->ipv6.rt6_stats->fib_rt_cache,
atomic_read(&net->ipv6.ip6_dst_ops.entries),
dst_entries_get_slow(&net->ipv6.ip6_dst_ops),
net->ipv6.rt6_stats->fib_discarded_routes);
return 0;
@ -2666,11 +2667,14 @@ static int __net_init ip6_route_net_init(struct net *net)
memcpy(&net->ipv6.ip6_dst_ops, &ip6_dst_ops_template,
sizeof(net->ipv6.ip6_dst_ops));
if (dst_entries_init(&net->ipv6.ip6_dst_ops) < 0)
goto out_ip6_dst_ops;
net->ipv6.ip6_null_entry = kmemdup(&ip6_null_entry_template,
sizeof(*net->ipv6.ip6_null_entry),
GFP_KERNEL);
if (!net->ipv6.ip6_null_entry)
goto out_ip6_dst_ops;
goto out_ip6_dst_entries;
net->ipv6.ip6_null_entry->dst.path =
(struct dst_entry *)net->ipv6.ip6_null_entry;
net->ipv6.ip6_null_entry->dst.ops = &net->ipv6.ip6_dst_ops;
@ -2720,6 +2724,8 @@ out_ip6_prohibit_entry:
out_ip6_null_entry:
kfree(net->ipv6.ip6_null_entry);
#endif
out_ip6_dst_entries:
dst_entries_destroy(&net->ipv6.ip6_dst_ops);
out_ip6_dst_ops:
goto out;
}
@ -2758,10 +2764,14 @@ int __init ip6_route_init(void)
if (!ip6_dst_ops_template.kmem_cachep)
goto out;
ret = register_pernet_subsys(&ip6_route_net_ops);
ret = dst_entries_init(&ip6_dst_blackhole_ops);
if (ret)
goto out_kmem_cache;
ret = register_pernet_subsys(&ip6_route_net_ops);
if (ret)
goto out_dst_entries;
ip6_dst_blackhole_ops.kmem_cachep = ip6_dst_ops_template.kmem_cachep;
/* Registering of the loopback is done before this portion of code,
@ -2808,6 +2818,8 @@ out_fib6_init:
fib6_gc_cleanup();
out_register_subsys:
unregister_pernet_subsys(&ip6_route_net_ops);
out_dst_entries:
dst_entries_destroy(&ip6_dst_blackhole_ops);
out_kmem_cache:
kmem_cache_destroy(ip6_dst_ops_template.kmem_cachep);
goto out;

10
net/ipv6/xfrm6_policy.c
View File

@ -199,7 +199,7 @@ static inline int xfrm6_garbage_collect(struct dst_ops *ops)
struct net *net = container_of(ops, struct net, xfrm.xfrm6_dst_ops);
xfrm6_policy_afinfo.garbage_collect(net);
return atomic_read(&ops->entries) > ops->gc_thresh * 2;
return dst_entries_get_fast(ops) > ops->gc_thresh * 2;
}
static void xfrm6_update_pmtu(struct dst_entry *dst, u32 mtu)
@ -255,7 +255,6 @@ static struct dst_ops xfrm6_dst_ops = {
.ifdown = xfrm6_dst_ifdown,
.local_out = __ip6_local_out,
.gc_thresh = 1024,
.entries = ATOMIC_INIT(0),
};
static struct xfrm_policy_afinfo xfrm6_policy_afinfo = {
@ -312,11 +311,13 @@ int __init xfrm6_init(void)
*/
gc_thresh = FIB6_TABLE_HASHSZ * 8;
xfrm6_dst_ops.gc_thresh = (gc_thresh < 1024) ? 1024 : gc_thresh;
dst_entries_init(&xfrm6_dst_ops);
ret = xfrm6_policy_init();
if (ret)
if (ret) {
dst_entries_destroy(&xfrm6_dst_ops);
goto out;
}
ret = xfrm6_state_init();
if (ret)
goto out_policy;
@ -341,4 +342,5 @@ void xfrm6_fini(void)
//xfrm6_input_fini();
xfrm6_policy_fini();
xfrm6_state_fini();
dst_entries_destroy(&xfrm6_dst_ops);
}