Commit 4103f8cd authored Mar 27, 2007 by Eric Dumazet Committed by David S. Miller Apr 25, 2007

[TCP]: tcp_memory_pressure and tcp_socket are__read_mostly candidates



tcp_memory_pressure and tcp_socket currently share a cache line with tcp_memory_allocated, tcp_sockets_allocated.
(Very hot cache line)
It makes sense to declare these variables as __read_mostly, to avoid false sharing on SMP.

ffffffff8081d9c0 B tcp_orphan_count
ffffffff8081d9c4 B tcp_memory_allocated
ffffffff8081d9c8 B tcp_sockets_allocated
ffffffff8081d9cc B tcp_memory_pressure
ffffffff8081d9d0 b tcp_md5sig_users
ffffffff8081d9d8 b tcp_md5sig_pool
ffffffff8081d9e0 b warntime.31570
ffffffff8081d9e8 b tcp_socket

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

parent 73417f61

net/ipv4/tcp.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -297,7 +297,7 @@ EXPORT_SYMBOL(tcp_sockets_allocated);
		* All the sk_stream_mem_schedule() is of this nature: accounting
		* is strict, actions are advisory and have some latency.
		*/
		int tcp_memory_pressure;
		int tcp_memory_pressure __read_mostly;

		EXPORT_SYMBOL(tcp_memory_pressure);

net/ipv4/tcp_ipv4.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -88,7 +88,7 @@ int sysctl_tcp_low_latency __read_mostly;
		#define ICMP_MIN_LENGTH 8

		/* Socket used for sending RSTs */
		static struct socket *tcp_socket;
		static struct socket *tcp_socket __read_mostly;

		void tcp_v4_send_check(struct sock sk, int len, struct sk_buff skb);

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