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authorEric Dumazet <eric.dumazet@gmail.com>2009-10-07 00:37:59 +0000
committerDavid S. Miller <davem@davemloft.net>2009-10-07 22:00:22 -0700
commitf86dcc5aa8c7908f2c287e7a211228df599e3e71 (patch)
tree1721c94d0254b337b0668b2e331771dfef4b142d /include
parent8a6dfd43d1891882f8ca05d73aa7735fb0edae3b (diff)
downloadop-kernel-dev-f86dcc5aa8c7908f2c287e7a211228df599e3e71.zip
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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>
Diffstat (limited to 'include')
-rw-r--r--include/linux/udp.h6
-rw-r--r--include/net/udp.h13
2 files changed, 13 insertions, 6 deletions
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 @@ static inline struct udphdr *udp_hdr(const struct sk_buff *skb)
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 udp_hslot {
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
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