netdev - [PATCH v3 net-next 4/4] tcp: shrink tcp_timewait

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Date:	Thu,  8 Oct 2015 19:33:24 -0700
From:	Eric Dumazet <edumazet@...gle.com>
To:	"David S . Miller" <davem@...emloft.net>
Cc:	netdev <netdev@...r.kernel.org>,
	Eric Dumazet <edumazet@...gle.com>,
	Eric Dumazet <eric.dumazet@...il.com>
Subject: [PATCH v3 net-next 4/4] tcp: shrink tcp_timewait_sock by 8 bytes

Reducing tcp_timewait_sock from 280 bytes to 272 bytes
allows SLAB to pack 15 objects per page instead of 14 (on x86)

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 include/linux/tcp.h | 4 ++--
 include/net/sock.h  | 2 ++
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index e442e6e9a365..86a7edaa6797 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -356,8 +356,8 @@ static inline struct tcp_sock *tcp_sk(const struct sock *sk)
 
 struct tcp_timewait_sock {
 	struct inet_timewait_sock tw_sk;
-	u32			  tw_rcv_nxt;
-	u32			  tw_snd_nxt;
+#define tw_rcv_nxt tw_sk.__tw_common.skc_tw_rcv_nxt
+#define tw_snd_nxt tw_sk.__tw_common.skc_tw_snd_nxt
 	u32			  tw_rcv_wnd;
 	u32			  tw_ts_offset;
 	u32			  tw_ts_recent;
diff --git a/include/net/sock.h b/include/net/sock.h
index fce12399fad4..288934da0ae3 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -229,6 +229,7 @@ struct sock_common {
 	union {
 		int		skc_incoming_cpu;
 		u32		skc_rcv_wnd;
+		u32		skc_tw_rcv_nxt; /* struct tcp_timewait_sock  */
 	};
 
 	atomic_t		skc_refcnt;
@@ -237,6 +238,7 @@ struct sock_common {
 	union {
 		u32		skc_rxhash;
 		u32		skc_window_clamp;
+		u32		skc_tw_snd_nxt; /* struct tcp_timewait_sock */
 	};
 	/* public: */
 };
-- 
2.6.0.rc2.230.g3dd15c0

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