udp: dynamically size hash tables at boot time
UDP_HTABLE_SIZE was initialy defined to 128, which is a bit small for
several setups.
4000 active UDP sockets -> 32 sockets per chain in average. An
incoming frame has to lookup all sockets to find best match, so long
chains hurt latency.
Instead of a fixed size hash table that cant be perfect for every
needs, let UDP stack choose its table size at boot time like tcp/ip
route, using alloc_large_system_hash() helper
Add an optional boot parameter, uhash_entries=x so that an admin can
force a size between 256 and 65536 if needed, like thash_entries and
rhash_entries.
dmesg logs two new lines :
[ 0.647039] UDP hash table entries: 512 (order: 0, 4096 bytes)
[ 0.647099] UDP Lite hash table entries: 512 (order: 0, 4096 bytes)
Maximal size on 64bit arches would be 65536 slots, ie 1 MBytes for non
debugging spinlocks.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 6fa7292..02df20b 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2589,6 +2589,9 @@
uart6850= [HW,OSS]
Format: <io>,<irq>
+ uhash_entries= [KNL,NET]
+ Set number of hash buckets for UDP/UDP-Lite connections
+
uhci-hcd.ignore_oc=
[USB] Ignore overcurrent events (default N).
Some badly-designed motherboards generate lots of
diff --git a/include/linux/udp.h b/include/linux/udp.h
index 0cf5c4c..832361e 100644
--- a/include/linux/udp.h
+++ b/include/linux/udp.h
@@ -45,11 +45,11 @@
return (struct udphdr *)skb_transport_header(skb);
}
-#define UDP_HTABLE_SIZE 128
+#define UDP_HTABLE_SIZE_MIN (CONFIG_BASE_SMALL ? 128 : 256)
-static inline int udp_hashfn(struct net *net, const unsigned num)
+static inline int udp_hashfn(struct net *net, unsigned num, unsigned mask)
{
- return (num + net_hash_mix(net)) & (UDP_HTABLE_SIZE - 1);
+ return (num + net_hash_mix(net)) & mask;
}
struct udp_sock {
diff --git a/include/net/udp.h b/include/net/udp.h
index f98abd2..22aa2e7 100644
--- a/include/net/udp.h
+++ b/include/net/udp.h
@@ -54,12 +54,19 @@
struct hlist_nulls_head head;
spinlock_t lock;
} __attribute__((aligned(2 * sizeof(long))));
+
struct udp_table {
- struct udp_hslot hash[UDP_HTABLE_SIZE];
+ struct udp_hslot *hash;
+ unsigned int mask;
+ unsigned int log;
};
extern struct udp_table udp_table;
-extern void udp_table_init(struct udp_table *);
-
+extern void udp_table_init(struct udp_table *, const char *);
+static inline struct udp_hslot *udp_hashslot(struct udp_table *table,
+ struct net *net, unsigned num)
+{
+ return &table->hash[udp_hashfn(net, num, table->mask)];
+}
/* Note: this must match 'valbool' in sock_setsockopt */
#define UDP_CSUM_NOXMIT 1
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 6ec6a8a..194bcdc 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -106,7 +106,7 @@
#include <net/xfrm.h>
#include "udp_impl.h"
-struct udp_table udp_table;
+struct udp_table udp_table __read_mostly;
EXPORT_SYMBOL(udp_table);
int sysctl_udp_mem[3] __read_mostly;
@@ -121,14 +121,16 @@
atomic_t udp_memory_allocated;
EXPORT_SYMBOL(udp_memory_allocated);
-#define PORTS_PER_CHAIN (65536 / UDP_HTABLE_SIZE)
+#define MAX_UDP_PORTS 65536
+#define PORTS_PER_CHAIN (MAX_UDP_PORTS / UDP_HTABLE_SIZE_MIN)
static int udp_lib_lport_inuse(struct net *net, __u16 num,
const struct udp_hslot *hslot,
unsigned long *bitmap,
struct sock *sk,
int (*saddr_comp)(const struct sock *sk1,
- const struct sock *sk2))
+ const struct sock *sk2),
+ unsigned int log)
{
struct sock *sk2;
struct hlist_nulls_node *node;
@@ -142,8 +144,7 @@
|| sk2->sk_bound_dev_if == sk->sk_bound_dev_if) &&
(*saddr_comp)(sk, sk2)) {
if (bitmap)
- __set_bit(sk2->sk_hash / UDP_HTABLE_SIZE,
- bitmap);
+ __set_bit(sk2->sk_hash >> log, bitmap);
else
return 1;
}
@@ -180,13 +181,15 @@
/*
* force rand to be an odd multiple of UDP_HTABLE_SIZE
*/
- rand = (rand | 1) * UDP_HTABLE_SIZE;
- for (last = first + UDP_HTABLE_SIZE; first != last; first++) {
- hslot = &udptable->hash[udp_hashfn(net, first)];
+ rand = (rand | 1) * (udptable->mask + 1);
+ for (last = first + udptable->mask + 1;
+ first != last;
+ first++) {
+ hslot = udp_hashslot(udptable, net, first);
bitmap_zero(bitmap, PORTS_PER_CHAIN);
spin_lock_bh(&hslot->lock);
udp_lib_lport_inuse(net, snum, hslot, bitmap, sk,
- saddr_comp);
+ saddr_comp, udptable->log);
snum = first;
/*
@@ -196,7 +199,7 @@
*/
do {
if (low <= snum && snum <= high &&
- !test_bit(snum / UDP_HTABLE_SIZE, bitmap))
+ !test_bit(snum >> udptable->log, bitmap))
goto found;
snum += rand;
} while (snum != first);
@@ -204,9 +207,10 @@
}
goto fail;
} else {
- hslot = &udptable->hash[udp_hashfn(net, snum)];
+ hslot = udp_hashslot(udptable, net, snum);
spin_lock_bh(&hslot->lock);
- if (udp_lib_lport_inuse(net, snum, hslot, NULL, sk, saddr_comp))
+ if (udp_lib_lport_inuse(net, snum, hslot, NULL, sk,
+ saddr_comp, 0))
goto fail_unlock;
}
found:
@@ -283,7 +287,7 @@
struct sock *sk, *result;
struct hlist_nulls_node *node;
unsigned short hnum = ntohs(dport);
- unsigned int hash = udp_hashfn(net, hnum);
+ unsigned int hash = udp_hashfn(net, hnum, udptable->mask);
struct udp_hslot *hslot = &udptable->hash[hash];
int score, badness;
@@ -1013,8 +1017,8 @@
{
if (sk_hashed(sk)) {
struct udp_table *udptable = sk->sk_prot->h.udp_table;
- unsigned int hash = udp_hashfn(sock_net(sk), sk->sk_hash);
- struct udp_hslot *hslot = &udptable->hash[hash];
+ struct udp_hslot *hslot = udp_hashslot(udptable, sock_net(sk),
+ sk->sk_hash);
spin_lock_bh(&hslot->lock);
if (sk_nulls_del_node_init_rcu(sk)) {
@@ -1169,7 +1173,7 @@
struct udp_table *udptable)
{
struct sock *sk;
- struct udp_hslot *hslot = &udptable->hash[udp_hashfn(net, ntohs(uh->dest))];
+ struct udp_hslot *hslot = udp_hashslot(udptable, net, ntohs(uh->dest));
int dif;
spin_lock(&hslot->lock);
@@ -1609,9 +1613,14 @@
struct udp_iter_state *state = seq->private;
struct net *net = seq_file_net(seq);
- for (state->bucket = start; state->bucket < UDP_HTABLE_SIZE; ++state->bucket) {
+ for (state->bucket = start; state->bucket <= state->udp_table->mask;
+ ++state->bucket) {
struct hlist_nulls_node *node;
struct udp_hslot *hslot = &state->udp_table->hash[state->bucket];
+
+ if (hlist_nulls_empty(&hslot->head))
+ continue;
+
spin_lock_bh(&hslot->lock);
sk_nulls_for_each(sk, node, &hslot->head) {
if (!net_eq(sock_net(sk), net))
@@ -1636,7 +1645,7 @@
} while (sk && (!net_eq(sock_net(sk), net) || sk->sk_family != state->family));
if (!sk) {
- if (state->bucket < UDP_HTABLE_SIZE)
+ if (state->bucket <= state->udp_table->mask)
spin_unlock_bh(&state->udp_table->hash[state->bucket].lock);
return udp_get_first(seq, state->bucket + 1);
}
@@ -1656,7 +1665,7 @@
static void *udp_seq_start(struct seq_file *seq, loff_t *pos)
{
struct udp_iter_state *state = seq->private;
- state->bucket = UDP_HTABLE_SIZE;
+ state->bucket = MAX_UDP_PORTS;
return *pos ? udp_get_idx(seq, *pos-1) : SEQ_START_TOKEN;
}
@@ -1678,7 +1687,7 @@
{
struct udp_iter_state *state = seq->private;
- if (state->bucket < UDP_HTABLE_SIZE)
+ if (state->bucket <= state->udp_table->mask)
spin_unlock_bh(&state->udp_table->hash[state->bucket].lock);
}
@@ -1738,7 +1747,7 @@
__u16 destp = ntohs(inet->dport);
__u16 srcp = ntohs(inet->sport);
- seq_printf(f, "%4d: %08X:%04X %08X:%04X"
+ seq_printf(f, "%5d: %08X:%04X %08X:%04X"
" %02X %08X:%08X %02X:%08lX %08X %5d %8d %lu %d %p %d%n",
bucket, src, srcp, dest, destp, sp->sk_state,
sk_wmem_alloc_get(sp),
@@ -1804,11 +1813,43 @@
}
#endif /* CONFIG_PROC_FS */
-void __init udp_table_init(struct udp_table *table)
+static __initdata unsigned long uhash_entries;
+static int __init set_uhash_entries(char *str)
{
- int i;
+ if (!str)
+ return 0;
+ uhash_entries = simple_strtoul(str, &str, 0);
+ if (uhash_entries && uhash_entries < UDP_HTABLE_SIZE_MIN)
+ uhash_entries = UDP_HTABLE_SIZE_MIN;
+ return 1;
+}
+__setup("uhash_entries=", set_uhash_entries);
- for (i = 0; i < UDP_HTABLE_SIZE; i++) {
+void __init udp_table_init(struct udp_table *table, const char *name)
+{
+ unsigned int i;
+
+ if (!CONFIG_BASE_SMALL)
+ table->hash = alloc_large_system_hash(name,
+ sizeof(struct udp_hslot),
+ uhash_entries,
+ 21, /* one slot per 2 MB */
+ 0,
+ &table->log,
+ &table->mask,
+ 64 * 1024);
+ /*
+ * Make sure hash table has the minimum size
+ */
+ if (CONFIG_BASE_SMALL || table->mask < UDP_HTABLE_SIZE_MIN - 1) {
+ table->hash = kmalloc(UDP_HTABLE_SIZE_MIN *
+ sizeof(struct udp_hslot), GFP_KERNEL);
+ if (!table->hash)
+ panic(name);
+ table->log = ilog2(UDP_HTABLE_SIZE_MIN);
+ table->mask = UDP_HTABLE_SIZE_MIN - 1;
+ }
+ for (i = 0; i <= table->mask; i++) {
INIT_HLIST_NULLS_HEAD(&table->hash[i].head, i);
spin_lock_init(&table->hash[i].lock);
}
@@ -1818,7 +1859,7 @@
{
unsigned long nr_pages, limit;
- udp_table_init(&udp_table);
+ udp_table_init(&udp_table, "UDP");
/* Set the pressure threshold up by the same strategy of TCP. It is a
* fraction of global memory that is up to 1/2 at 256 MB, decreasing
* toward zero with the amount of memory, with a floor of 128 pages.
diff --git a/net/ipv4/udplite.c b/net/ipv4/udplite.c
index 95248d7..470c504 100644
--- a/net/ipv4/udplite.c
+++ b/net/ipv4/udplite.c
@@ -12,7 +12,7 @@
*/
#include "udp_impl.h"
-struct udp_table udplite_table;
+struct udp_table udplite_table __read_mostly;
EXPORT_SYMBOL(udplite_table);
static int udplite_rcv(struct sk_buff *skb)
@@ -110,7 +110,7 @@
void __init udplite4_register(void)
{
- udp_table_init(&udplite_table);
+ udp_table_init(&udplite_table, "UDP-Lite");
if (proto_register(&udplite_prot, 1))
goto out_register_err;
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index c6a303e..ff778c1 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -132,7 +132,7 @@
struct sock *sk, *result;
struct hlist_nulls_node *node;
unsigned short hnum = ntohs(dport);
- unsigned int hash = udp_hashfn(net, hnum);
+ unsigned int hash = udp_hashfn(net, hnum, udptable->mask);
struct udp_hslot *hslot = &udptable->hash[hash];
int score, badness;
@@ -452,7 +452,7 @@
{
struct sock *sk, *sk2;
const struct udphdr *uh = udp_hdr(skb);
- struct udp_hslot *hslot = &udptable->hash[udp_hashfn(net, ntohs(uh->dest))];
+ struct udp_hslot *hslot = udp_hashslot(udptable, net, ntohs(uh->dest));
int dif;
spin_lock(&hslot->lock);
@@ -1197,7 +1197,7 @@
destp = ntohs(inet->dport);
srcp = ntohs(inet->sport);
seq_printf(seq,
- "%4d: %08X%08X%08X%08X:%04X %08X%08X%08X%08X:%04X "
+ "%5d: %08X%08X%08X%08X:%04X %08X%08X%08X%08X:%04X "
"%02X %08X:%08X %02X:%08lX %08X %5d %8d %lu %d %p %d\n",
bucket,
src->s6_addr32[0], src->s6_addr32[1],