tcp: shrink tcp6_timewait_sock by one cache line
While working on tcp listener refactoring, I found that it
would really make things easier if sock_common could include
the IPv6 addresses needed in the lookups, instead of doing
very complex games to get their values (depending on sock
being SYN_RECV, ESTABLISHED, TIME_WAIT)
For this to happen, I need to be sure that tcp6_timewait_sock
and tcp_timewait_sock consume same number of cache lines.
This is possible if we only use 32bits for tw_ttd, as we remove
one 32bit hole in inet_timewait_sock
inet_tw_time_stamp() is defined and used, even if its current
implementation looks like tcp_time_stamp : We might need finer
resolution for tcp_time_stamp in the future.
Before patch : sizeof(struct tcp6_timewait_sock) = 0xc8
After patch : sizeof(struct tcp6_timewait_sock) = 0xc0
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/inet_timewait_sock.h b/include/net/inet_timewait_sock.h
index 48fd356..f528d1b 100644
--- a/include/net/inet_timewait_sock.h
+++ b/include/net/inet_timewait_sock.h
@@ -58,6 +58,11 @@
# define INET_TWDR_RECYCLE_TICK (12 + 2 - INET_TWDR_RECYCLE_SLOTS_LOG)
#endif
+static inline u32 inet_tw_time_stamp(void)
+{
+ return jiffies;
+}
+
/* TIME_WAIT reaping mechanism. */
#define INET_TWDR_TWKILL_SLOTS 8 /* Please keep this a power of 2. */
@@ -130,7 +135,7 @@
tw_tos : 8,
tw_ipv6_offset : 16;
kmemcheck_bitfield_end(flags);
- unsigned long tw_ttd;
+ u32 tw_ttd;
struct inet_bind_bucket *tw_tb;
struct hlist_node tw_death_node;
};