Commit 96f817fe authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

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: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 40dc9ab2

include/net/inet_timewait_sock.h

+6 −1
Original line number Diff line number Diff line
@@ -58,6 +58,11 @@ struct inet_hashinfo; 
# 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 @@ struct inet_timewait_sock { 
				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;

};

net/ipv4/inet_diag.c

+3 −3
Original line number Diff line number Diff line
@@ -222,7 +222,7 @@ static int inet_twsk_diag_fill(struct inet_timewait_sock *tw, 
			       u32 portid, u32 seq, u16 nlmsg_flags,

			       const struct nlmsghdr *unlh)

{

	long tmo;

	s32 tmo;

	struct inet_diag_msg *r;

	struct nlmsghdr *nlh;
@@ -234,7 +234,7 @@ static int inet_twsk_diag_fill(struct inet_timewait_sock *tw, 
	r = nlmsg_data(nlh);

	BUG_ON(tw->tw_state != TCP_TIME_WAIT);



	tmo = tw->tw_ttd - jiffies;

	tmo = tw->tw_ttd - inet_tw_time_stamp();

	if (tmo < 0)

		tmo = 0;
@@ -248,7 +248,7 @@ static int inet_twsk_diag_fill(struct inet_timewait_sock *tw, 
	r->id.idiag_dst[0]    = tw->tw_daddr;

	r->idiag_state	      = tw->tw_substate;

	r->idiag_timer	      = 3;

	r->idiag_expires      = DIV_ROUND_UP(tmo * 1000, HZ);

	r->idiag_expires      = jiffies_to_msecs(tmo);

	r->idiag_rqueue	      = 0;

	r->idiag_wqueue	      = 0;

	r->idiag_uid	      = 0;

net/ipv4/inet_timewait_sock.c

+2 −2
Original line number Diff line number Diff line
@@ -387,11 +387,11 @@ void inet_twsk_schedule(struct inet_timewait_sock *tw, 
			if (slot >= INET_TWDR_TWKILL_SLOTS)

				slot = INET_TWDR_TWKILL_SLOTS - 1;

		}

		tw->tw_ttd = jiffies + timeo;

		tw->tw_ttd = inet_tw_time_stamp() + timeo;

		slot = (twdr->slot + slot) & (INET_TWDR_TWKILL_SLOTS - 1);

		list = &twdr->cells[slot];

	} else {

		tw->tw_ttd = jiffies + (slot << INET_TWDR_RECYCLE_TICK);

		tw->tw_ttd = inet_tw_time_stamp() + (slot << INET_TWDR_RECYCLE_TICK);



		if (twdr->twcal_hand < 0) {

			twdr->twcal_hand = 0;

net/ipv6/tcp_ipv6.c

+1 −1
Original line number Diff line number Diff line
@@ -1811,7 +1811,7 @@ static void get_timewait6_sock(struct seq_file *seq, 
	const struct in6_addr *dest, *src;

	__u16 destp, srcp;

	const struct inet6_timewait_sock *tw6 = inet6_twsk((struct sock *)tw);

	long delta = tw->tw_ttd - jiffies;

	s32 delta = tw->tw_ttd - inet_tw_time_stamp();



	dest = &tw6->tw_v6_daddr;

	src  = &tw6->tw_v6_rcv_saddr;

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