[NET]: use __read_mostly on kmem_cache_t , DEFINE_SNMP_STAT pointers

This patch puts mostly read only data in the right section
(read_mostly), to help sharing of these data between CPUS without
memory ping pongs.

On one of my production machine, tcp_statistics was sitting in a
heavily modified cache line, so *every* SNMP update had to force a
reload.

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/bridge/br_fdb.c

@@ -23,7 +23,7 @@
 #include <asm/atomic.h>
 #include "br_private.h"
 
-static kmem_cache_t *br_fdb_cache;
+static kmem_cache_t *br_fdb_cache __read_mostly;
 static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
 		      const unsigned char *addr);
 

net/core/flow.c

@@ -42,7 +42,7 @@ static DEFINE_PER_CPU(struct flow_cache_entry **, flow_tables) = { NULL };
 
 #define flow_table(cpu) (per_cpu(flow_tables, cpu))
 
-static kmem_cache_t *flow_cachep;
+static kmem_cache_t *flow_cachep __read_mostly;
 
 static int flow_lwm, flow_hwm;
 

net/core/skbuff.c

@@ -68,8 +68,8 @@
 #include <asm/uaccess.h>
 #include <asm/system.h>
 
-static kmem_cache_t *skbuff_head_cache;
-static kmem_cache_t *skbuff_fclone_cache;
+static kmem_cache_t *skbuff_head_cache __read_mostly;
+static kmem_cache_t *skbuff_fclone_cache __read_mostly;
 
 struct timeval __read_mostly skb_tv_base;
 

net/dccp/ccids/ccid3.c

@@ -85,7 +85,7 @@ static int ccid3_debug;
 static struct dccp_tx_hist *ccid3_tx_hist;
 static struct dccp_rx_hist *ccid3_rx_hist;
 
-static kmem_cache_t *ccid3_loss_interval_hist_slab;
+static kmem_cache_t *ccid3_loss_interval_hist_slab __read_mostly;
 
 static inline struct ccid3_loss_interval_hist_entry *
 	ccid3_loss_interval_hist_entry_new(const unsigned int __nocast prio)

net/dccp/proto.c

@@ -39,7 +39,7 @@
 #include "ccid.h"
 #include "dccp.h"
 
-DEFINE_SNMP_STAT(struct dccp_mib, dccp_statistics);
+DEFINE_SNMP_STAT(struct dccp_mib, dccp_statistics) __read_mostly;
 
 atomic_t dccp_orphan_count = ATOMIC_INIT(0);
 

net/decnet/dn_table.c

@@ -79,7 +79,7 @@ for( ; ((f) = *(fp)) != NULL && dn_key_eq((f)->fn_key, (key)); (fp) = &(f)->fn_n
 static DEFINE_RWLOCK(dn_fib_tables_lock);
 struct dn_fib_table *dn_fib_tables[RT_TABLE_MAX + 1];
 
-static kmem_cache_t *dn_hash_kmem;
+static kmem_cache_t *dn_hash_kmem __read_mostly;
 static int dn_fib_hash_zombies;
 
 static inline dn_fib_idx_t dn_hash(dn_fib_key_t key, struct dn_zone *dz)

net/ipv4/af_inet.c

@@ -113,7 +113,7 @@
 #include <linux/mroute.h>
 #endif
 
-DEFINE_SNMP_STAT(struct linux_mib, net_statistics);
+DEFINE_SNMP_STAT(struct linux_mib, net_statistics) __read_mostly;
 
 extern void ip_mc_drop_socket(struct sock *sk);
 

net/ipv4/fib_hash.c

@@ -45,8 +45,8 @@
 
 #include "fib_lookup.h"
 
-static kmem_cache_t *fn_hash_kmem;
-static kmem_cache_t *fn_alias_kmem;
+static kmem_cache_t *fn_hash_kmem __read_mostly;
+static kmem_cache_t *fn_alias_kmem __read_mostly;
 
 struct fib_node {
 	struct hlist_node	fn_hash;

net/ipv4/fib_trie.c

@@ -166,7 +166,7 @@ static struct tnode *halve(struct trie *t, struct tnode *tn);
 static void tnode_free(struct tnode *tn);
 static void trie_dump_seq(struct seq_file *seq, struct trie *t);
 
-static kmem_cache_t *fn_alias_kmem;
+static kmem_cache_t *fn_alias_kmem __read_mostly;
 static struct trie *trie_local = NULL, *trie_main = NULL;
 
 

net/ipv4/icmp.c

@@ -114,7 +114,7 @@ struct icmp_bxm {
 /*
  *	Statistics
  */
-DEFINE_SNMP_STAT(struct icmp_mib, icmp_statistics);
+DEFINE_SNMP_STAT(struct icmp_mib, icmp_statistics) __read_mostly;
 
 /* An array of errno for error messages from dest unreach. */
 /* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */

net/ipv4/inetpeer.c

@@ -73,7 +73,7 @@
 /* Exported for inet_getid inline function.  */
 DEFINE_SPINLOCK(inet_peer_idlock);
 
-static kmem_cache_t *peer_cachep;
+static kmem_cache_t *peer_cachep __read_mostly;
 
 #define node_height(x) x->avl_height
 static struct inet_peer peer_fake_node = {

net/ipv4/ip_input.c

@@ -150,7 +150,7 @@
  *	SNMP management statistics
  */
 
-DEFINE_SNMP_STAT(struct ipstats_mib, ip_statistics);
+DEFINE_SNMP_STAT(struct ipstats_mib, ip_statistics) __read_mostly;
 
 /*
  *	Process Router Attention IP option

net/ipv4/ipmr.c

@@ -103,7 +103,7 @@ static DEFINE_SPINLOCK(mfc_unres_lock);
    In this case data path is free of exclusive locks at all.
  */
 
-static kmem_cache_t *mrt_cachep;
+static kmem_cache_t *mrt_cachep __read_mostly;
 
 static int ip_mr_forward(struct sk_buff *skb, struct mfc_cache *cache, int local);
 static int ipmr_cache_report(struct sk_buff *pkt, vifi_t vifi, int assert);

net/ipv4/ipvs/ip_vs_conn.c

@@ -40,7 +40,7 @@
 static struct list_head *ip_vs_conn_tab;
 
 /*  SLAB cache for IPVS connections */
-static kmem_cache_t *ip_vs_conn_cachep;
+static kmem_cache_t *ip_vs_conn_cachep __read_mostly;
 
 /*  counter for current IPVS connections */
 static atomic_t ip_vs_conn_count = ATOMIC_INIT(0);

net/ipv4/netfilter/ip_conntrack_core.c

@@ -70,8 +70,8 @@ static LIST_HEAD(helpers);
 unsigned int ip_conntrack_htable_size = 0;
 int ip_conntrack_max;
 struct list_head *ip_conntrack_hash;
-static kmem_cache_t *ip_conntrack_cachep;
-static kmem_cache_t *ip_conntrack_expect_cachep;
+static kmem_cache_t *ip_conntrack_cachep __read_mostly;
+static kmem_cache_t *ip_conntrack_expect_cachep __read_mostly;
 struct ip_conntrack ip_conntrack_untracked;
 unsigned int ip_ct_log_invalid;
 static LIST_HEAD(unconfirmed);

net/ipv4/netfilter/ipt_hashlimit.c

@@ -94,7 +94,7 @@ struct ipt_hashlimit_htable {
 static DEFINE_SPINLOCK(hashlimit_lock);	/* protects htables list */
 static DECLARE_MUTEX(hlimit_mutex);	/* additional checkentry protection */
 static HLIST_HEAD(hashlimit_htables);
-static kmem_cache_t *hashlimit_cachep;
+static kmem_cache_t *hashlimit_cachep __read_mostly;
 
 static inline int dst_cmp(const struct dsthash_ent *ent, struct dsthash_dst *b)
 {

net/ipv4/tcp.c

@@ -269,7 +269,7 @@
 
 int sysctl_tcp_fin_timeout = TCP_FIN_TIMEOUT;
 
-DEFINE_SNMP_STAT(struct tcp_mib, tcp_statistics);
+DEFINE_SNMP_STAT(struct tcp_mib, tcp_statistics) __read_mostly;
 
 atomic_t tcp_orphan_count = ATOMIC_INIT(0);
 

net/ipv4/udp.c

@@ -113,7 +113,7 @@
  *	Snmp MIB for the UDP layer
  */
 
-DEFINE_SNMP_STAT(struct udp_mib, udp_statistics);
+DEFINE_SNMP_STAT(struct udp_mib, udp_statistics) __read_mostly;
 
 struct hlist_head udp_hash[UDP_HTABLE_SIZE];
 DEFINE_RWLOCK(udp_hash_lock);

net/ipv6/icmp.c

@@ -67,7 +67,7 @@
 #include <asm/uaccess.h>
 #include <asm/system.h>
 
-DEFINE_SNMP_STAT(struct icmpv6_mib, icmpv6_statistics);
+DEFINE_SNMP_STAT(struct icmpv6_mib, icmpv6_statistics) __read_mostly;
 
 /*
  *	The ICMP socket(s). This is the most convenient way to flow control

net/ipv6/ip6_fib.c

@@ -49,7 +49,7 @@
 
 struct rt6_statistics	rt6_stats;
 
-static kmem_cache_t * fib6_node_kmem;
+static kmem_cache_t * fib6_node_kmem __read_mostly;
 
 enum fib_walk_state_t
 {

net/ipv6/ipv6_sockglue.c

@@ -55,7 +55,7 @@
 
 #include <asm/uaccess.h>
 
-DEFINE_SNMP_STAT(struct ipstats_mib, ipv6_statistics);
+DEFINE_SNMP_STAT(struct ipstats_mib, ipv6_statistics) __read_mostly;
 
 static struct packet_type ipv6_packet_type = {
 	.type = __constant_htons(ETH_P_IPV6), 

net/ipv6/udp.c

@@ -59,7 +59,7 @@
 #include <linux/proc_fs.h>
 #include <linux/seq_file.h>
 
-DEFINE_SNMP_STAT(struct udp_mib, udp_stats_in6);
+DEFINE_SNMP_STAT(struct udp_mib, udp_stats_in6) __read_mostly;
 
 /* Grrr, addr_type already calculated by caller, but I don't want
  * to add some silly "cookie" argument to this method just for that.

net/ipv6/xfrm6_tunnel.c

@@ -79,7 +79,7 @@ static u32 xfrm6_tunnel_spi;
 #define XFRM6_TUNNEL_SPI_MIN	1
 #define XFRM6_TUNNEL_SPI_MAX	0xffffffff
 
-static kmem_cache_t *xfrm6_tunnel_spi_kmem;
+static kmem_cache_t *xfrm6_tunnel_spi_kmem __read_mostly;
 
 #define XFRM6_TUNNEL_SPI_BYADDR_HSIZE 256
 #define XFRM6_TUNNEL_SPI_BYSPI_HSIZE 256

net/sctp/protocol.c

@@ -62,7 +62,7 @@
 /* Global data structures. */
 struct sctp_globals sctp_globals;
 struct proc_dir_entry	*proc_net_sctp;
-DEFINE_SNMP_STAT(struct sctp_mib, sctp_statistics);
+DEFINE_SNMP_STAT(struct sctp_mib, sctp_statistics) __read_mostly;
 
 struct idr sctp_assocs_id;
 DEFINE_SPINLOCK(sctp_assocs_id_lock);
@@ -78,8 +78,8 @@ static struct sctp_pf *sctp_pf_inet_specific;
 static struct sctp_af *sctp_af_v4_specific;
 static struct sctp_af *sctp_af_v6_specific;
 
-kmem_cache_t *sctp_chunk_cachep;
-kmem_cache_t *sctp_bucket_cachep;
+kmem_cache_t *sctp_chunk_cachep __read_mostly;
+kmem_cache_t *sctp_bucket_cachep __read_mostly;
 
 extern int sctp_snmp_proc_init(void);
 extern int sctp_snmp_proc_exit(void);

net/socket.c

@@ -274,7 +274,7 @@ int move_addr_to_user(void *kaddr, int klen, void __user *uaddr, int __user *ule
 
 #define SOCKFS_MAGIC 0x534F434B
 
-static kmem_cache_t * sock_inode_cachep;
+static kmem_cache_t * sock_inode_cachep __read_mostly;
 
 static struct inode *sock_alloc_inode(struct super_block *sb)
 {
@@ -333,7 +333,7 @@ static struct super_block *sockfs_get_sb(struct file_system_type *fs_type,
 	return get_sb_pseudo(fs_type, "socket:", &sockfs_ops, SOCKFS_MAGIC);
 }
 
-static struct vfsmount *sock_mnt;
+static struct vfsmount *sock_mnt __read_mostly;
 
 static struct file_system_type sock_fs_type = {
 	.name =		"sockfs",

net/sunrpc/rpc_pipe.c

@@ -28,13 +28,13 @@
 #include <linux/workqueue.h>
 #include <linux/sunrpc/rpc_pipe_fs.h>
 
-static struct vfsmount *rpc_mount;
+static struct vfsmount *rpc_mount __read_mostly;
 static int rpc_mount_count;
 
 static struct file_system_type rpc_pipe_fs_type;
 
 
-static kmem_cache_t *rpc_inode_cachep;
+static kmem_cache_t *rpc_inode_cachep __read_mostly;
 
 #define RPC_UPCALL_TIMEOUT (30*HZ)
 

net/sunrpc/sched.c

@@ -34,10 +34,10 @@ static int			rpc_task_id;
 #define RPC_BUFFER_MAXSIZE	(2048)
 #define RPC_BUFFER_POOLSIZE	(8)
 #define RPC_TASK_POOLSIZE	(8)
-static kmem_cache_t	*rpc_task_slabp;
-static kmem_cache_t	*rpc_buffer_slabp;
-static mempool_t	*rpc_task_mempool;
-static mempool_t	*rpc_buffer_mempool;
+static kmem_cache_t	*rpc_task_slabp __read_mostly;
+static kmem_cache_t	*rpc_buffer_slabp __read_mostly;
+static mempool_t	*rpc_task_mempool __read_mostly;
+static mempool_t	*rpc_buffer_mempool __read_mostly;
 
 static void			__rpc_default_timer(struct rpc_task *task);
 static void			rpciod_killall(void);

net/xfrm/xfrm_input.c

@@ -12,7 +12,7 @@
 #include <net/ip.h>
 #include <net/xfrm.h>
 
-static kmem_cache_t *secpath_cachep;
+static kmem_cache_t *secpath_cachep __read_mostly;
 
 void __secpath_destroy(struct sec_path *sp)
 {

net/xfrm/xfrm_policy.c

@@ -37,7 +37,7 @@ EXPORT_SYMBOL(xfrm_policy_list);
 static DEFINE_RWLOCK(xfrm_policy_afinfo_lock);
 static struct xfrm_policy_afinfo *xfrm_policy_afinfo[NPROTO];
 
-static kmem_cache_t *xfrm_dst_cache;
+static kmem_cache_t *xfrm_dst_cache __read_mostly;
 
 static struct work_struct xfrm_policy_gc_work;
 static struct list_head xfrm_policy_gc_list =