netdev - [PATCH net-next 10/20] net: cache align tcp_memory_allocated, tcp_sockets

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Date:   Mon, 15 Nov 2021 11:02:39 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     netdev <netdev@...r.kernel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Eric Dumazet <eric.dumazet@...il.com>,
        Soheil Hassas Yeganeh <soheil@...gle.com>,
        Neal Cardwell <ncardwell@...gle.com>,
        Arjun Roy <arjunroy@...gle.com>
Subject: [PATCH net-next 10/20] net: cache align tcp_memory_allocated, tcp_sockets_allocated

From: Eric Dumazet <edumazet@...gle.com>

tcp_memory_allocated and tcp_sockets_allocated often share
a common cache line, source of false sharing.

Also take care of udp_memory_allocated and mptcp_sockets_allocated.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 net/ipv4/tcp.c       | 4 ++--
 net/ipv4/udp.c       | 2 +-
 net/mptcp/protocol.c | 2 +-
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 4fa4b29260bd4c08da70b3fb199e3459013114f3..862e8cb8dda51e76300a427783a7d8c32e82cc7f 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -292,7 +292,7 @@ EXPORT_PER_CPU_SYMBOL_GPL(tcp_orphan_count);
 long sysctl_tcp_mem[3] __read_mostly;
 EXPORT_SYMBOL(sysctl_tcp_mem);
 
-atomic_long_t tcp_memory_allocated;	/* Current allocated memory. */
+atomic_long_t tcp_memory_allocated ____cacheline_aligned_in_smp;	/* Current allocated memory. */
 EXPORT_SYMBOL(tcp_memory_allocated);
 
 #if IS_ENABLED(CONFIG_SMC)
@@ -303,7 +303,7 @@ EXPORT_SYMBOL(tcp_have_smc);
 /*
  * Current number of TCP sockets.
  */
-struct percpu_counter tcp_sockets_allocated;
+struct percpu_counter tcp_sockets_allocated ____cacheline_aligned_in_smp;
 EXPORT_SYMBOL(tcp_sockets_allocated);
 
 /*
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 319dd7bbfe33d64d25c36bc3a1cd3bd4caf0a779..d3cea98a5d5dbf4deea5b06bd95c38eebccd6a55 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -122,7 +122,7 @@ EXPORT_SYMBOL(udp_table);
 long sysctl_udp_mem[3] __read_mostly;
 EXPORT_SYMBOL(sysctl_udp_mem);
 
-atomic_long_t udp_memory_allocated;
+atomic_long_t udp_memory_allocated ____cacheline_aligned_in_smp;
 EXPORT_SYMBOL(udp_memory_allocated);
 
 #define MAX_UDP_PORTS 65536
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index b7e32e316738b88d4b9f907f584b12785e396dae..6db93da59843a830c00e8707b7a35f90dfe8047d 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -48,7 +48,7 @@ enum {
 	MPTCP_CMSG_TS = BIT(0),
 };
 
-static struct percpu_counter mptcp_sockets_allocated;
+static struct percpu_counter mptcp_sockets_allocated ____cacheline_aligned_in_smp;
 
 static void __mptcp_destroy_sock(struct sock *sk);
 static void __mptcp_check_send_data_fin(struct sock *sk);
-- 
2.34.0.rc1.387.gb447b232ab-goog