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authorEric Dumazet <eric.dumazet@gmail.com>2010-10-08 06:37:34 +0000
committerDavid S. Miller <davem@davemloft.net>2010-10-11 13:06:53 -0700
commitfc66f95c68b6d4535a0ea2ea15d5cf626e310956 (patch)
treeac3a7f08ad741a67ff683bf93e5669ddcae95ed7 /net/ipv4
parent0ed8ddf4045fcfcac36bad753dc4046118c603ec (diff)
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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>
Diffstat (limited to 'net/ipv4')
-rw-r--r--net/ipv4/route.c36
-rw-r--r--net/ipv4/xfrm4_policy.c4
2 files changed, 24 insertions, 16 deletions
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 3888f6b..0755aa4 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -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),
diff --git a/net/ipv4/xfrm4_policy.c b/net/ipv4/xfrm4_policy.c
index a580349..4464f3b 100644
--- a/net/ipv4/xfrm4_policy.c
+++ b/net/ipv4/xfrm4_policy.c
@@ -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();