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ipv6: Move ipv6_fl_list from ipv6_pinfo to inet_sock.

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In {tcp6,udp6,raw6}_sock, struct ipv6_pinfo is always placed at
the beginning of a new cache line because

  1. __alignof__(struct tcp_sock) is 64 due to ____cacheline_aligned
     of __cacheline_group_begin(tcp_sock_write_tx)

  2. __alignof__(struct udp_sock) is 64 due to ____cacheline_aligned
     of struct numa_drop_counters

  3. in raw6_sock, struct numa_drop_counters is placed before
     struct ipv6_pinfo

.  struct ipv6_pinfo is 136 bytes, but the last cache line is
only used by ipv6_fl_list:

  $ pahole -C ipv6_pinfo vmlinux
  struct ipv6_pinfo {
  ...
  	/* --- cacheline 2 boundary (128 bytes) --- */
  	struct ipv6_fl_socklist *  ipv6_fl_list;         /*   128     8 */

  	/* size: 136, cachelines: 3, members: 23 */

Let's move ipv6_fl_list from struct ipv6_pinfo to struct inet_sock
to save a full cache line for {tcp6,udp6,raw6}_sock.

Now, struct ipv6_pinfo is 128 bytes, and {tcp6,udp6,raw6}_sock have
64 bytes less, while {tcp,udp,raw}_sock retain the same size.

Before:

  # grep -E "^(RAW|UDP[^L\-]|TCP)" /proc/slabinfo | awk '{print $1, "\t", $4}'
  RAWv6 	 1408
  UDPv6 	 1472
  TCPv6 	 2560
  RAW 		 1152
  UDP	 	 1280
  TCP 		 2368

After:

  # grep -E "^(RAW|UDP[^L\-]|TCP)" /proc/slabinfo | awk '{print $1, "\t", $4}'
  RAWv6 	 1344
  UDPv6 	 1408
  TCPv6 	 2496
  RAW 		 1152
  UDP	 	 1280
  TCP 		 2368

Also, ipv6_fl_list and inet_flags (SNDFLOW bit) are placed in the
same cache line.

  $ pahole -C inet_sock vmlinux
  ...
  	/* --- cacheline 11 boundary (704 bytes) was 56 bytes ago --- */
  	struct ipv6_pinfo *        pinet6;               /*   760     8 */
  	/* --- cacheline 12 boundary (768 bytes) --- */
  	struct ipv6_fl_socklist *  ipv6_fl_list;         /*   768     8 */
  	unsigned long              inet_flags;           /*   776     8 */

Doc churn is due to the insufficient Type column (only 1 space short).

Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20251014224210.2964778-1-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Kuniyuki Iwashima 2025-10-14 22:42:07 +00:00 • committed by Jakub Kicinski
parent 0746da0176
commit 1c17f4373d
7 changed files with 76 additions and 74 deletions
Download patch file Download diff file Expand all files Collapse all files

79
Documentation/networking/net_cachelines/inet_sock.rst
View file

@ -5,42 +5,43 @@
inet_sock struct fast path usage breakdown
==========================================
======================= ===================== =================== =================== ======================================================================================================
Type Name fastpath_tx_access fastpath_rx_access comment
======================= ===================== =================== =================== ======================================================================================================
struct sock sk read_mostly read_mostly tcp_init_buffer_space,tcp_init_transfer,tcp_finish_connect,tcp_connect,tcp_send_rcvq,tcp_send_syn_data
struct ipv6_pinfo* pinet6
be16 inet_sport read_mostly __tcp_transmit_skb
be32 inet_daddr read_mostly ip_select_ident_segs
be32 inet_rcv_saddr
be16 inet_dport read_mostly __tcp_transmit_skb
u16 inet_num
be32 inet_saddr
s16 uc_ttl read_mostly __ip_queue_xmit/ip_select_ttl
u16 cmsg_flags
struct ip_options_rcu* inet_opt read_mostly __ip_queue_xmit
u16 inet_id read_mostly ip_select_ident_segs
u8 tos read_mostly ip_queue_xmit
u8 min_ttl
u8 mc_ttl
u8 pmtudisc
u8:1 recverr
u8:1 is_icsk
u8:1 freebind
u8:1 hdrincl
u8:1 mc_loop
u8:1 transparent
u8:1 mc_all
u8:1 nodefrag
u8:1 bind_address_no_port
u8:1 recverr_rfc4884
u8:1 defer_connect read_mostly tcp_sendmsg_fastopen
u8 rcv_tos
u8 convert_csum
int uc_index
int mc_index
be32 mc_addr
struct ip_mc_socklist* mc_list
struct inet_cork_full cork read_mostly __tcp_transmit_skb
struct local_port_range
======================= ===================== =================== =================== ======================================================================================================
======================== ===================== =================== =================== ======================================================================================================
Type Name fastpath_tx_access fastpath_rx_access comment
======================== ===================== =================== =================== ======================================================================================================
struct sock sk read_mostly read_mostly tcp_init_buffer_space,tcp_init_transfer,tcp_finish_connect,tcp_connect,tcp_send_rcvq,tcp_send_syn_data
struct ipv6_pinfo* pinet6
struct ipv6_fl_socklist* ipv6_fl_list read_mostly tcp_v6_connect,__ip6_datagram_connect,udpv6_sendmsg,rawv6_sendmsg
be16 inet_sport read_mostly __tcp_transmit_skb
be32 inet_daddr read_mostly ip_select_ident_segs
be32 inet_rcv_saddr
be16 inet_dport read_mostly __tcp_transmit_skb
u16 inet_num
be32 inet_saddr
s16 uc_ttl read_mostly __ip_queue_xmit/ip_select_ttl
u16 cmsg_flags
struct ip_options_rcu* inet_opt read_mostly __ip_queue_xmit
u16 inet_id read_mostly ip_select_ident_segs
u8 tos read_mostly ip_queue_xmit
u8 min_ttl
u8 mc_ttl
u8 pmtudisc
u8:1 recverr
u8:1 is_icsk
u8:1 freebind
u8:1 hdrincl
u8:1 mc_loop
u8:1 transparent
u8:1 mc_all
u8:1 nodefrag
u8:1 bind_address_no_port
u8:1 recverr_rfc4884
u8:1 defer_connect read_mostly tcp_sendmsg_fastopen
u8 rcv_tos
u8 convert_csum
int uc_index
int mc_index
be32 mc_addr
struct ip_mc_socklist* mc_list
struct inet_cork_full cork read_mostly __tcp_transmit_skb
struct local_port_range
======================== ===================== =================== =================== ======================================================================================================

4
drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_cm.c
View file

@ -1199,12 +1199,12 @@ static struct sock *chtls_recv_sock(struct sock *lsk,
struct ipv6_pinfo *newnp = inet6_sk(newsk);
struct ipv6_pinfo *np = inet6_sk(lsk);
inet_sk(newsk)->pinet6 = &newtcp6sk->inet6;
newinet->pinet6 = &newtcp6sk->inet6;
newinet->ipv6_fl_list = NULL;
memcpy(newnp, np, sizeof(struct ipv6_pinfo));
newsk->sk_v6_daddr = treq->ir_v6_rmt_addr;
newsk->sk_v6_rcv_saddr = treq->ir_v6_loc_addr;
inet6_sk(newsk)->saddr = treq->ir_v6_loc_addr;
newnp->ipv6_fl_list = NULL;
newnp->pktoptions = NULL;
newsk->sk_bound_dev_if = treq->ir_iif;
newinet->inet_opt = NULL;

1
include/linux/ipv6.h
View file

@ -271,7 +271,6 @@ struct ipv6_pinfo {
struct ipv6_mc_socklist __rcu *ipv6_mc_list;
struct ipv6_ac_socklist *ipv6_ac_list;
struct ipv6_fl_socklist __rcu *ipv6_fl_list;
};
/* We currently use available bits from inet_sk(sk)->inet_flags,

1
include/net/inet_sock.h
View file

@ -214,6 +214,7 @@ struct inet_sock {
struct sock sk;
#if IS_ENABLED(CONFIG_IPV6)
struct ipv6_pinfo *pinet6;
struct ipv6_fl_socklist __rcu *ipv6_fl_list;
#endif
/* Socket demultiplex comparisons on incoming packets. */
#define inet_daddr sk.__sk_common.skc_daddr

44
net/ipv6/ip6_flowlabel.c
View file

@ -66,8 +66,8 @@ EXPORT_SYMBOL(ipv6_flowlabel_exclusive);
fl != NULL; \
fl = rcu_dereference(fl->next))
#define for_each_sk_fl_rcu(np, sfl) \
for (sfl = rcu_dereference(np->ipv6_fl_list); \
#define for_each_sk_fl_rcu(sk, sfl) \
for (sfl = rcu_dereference(inet_sk(sk)->ipv6_fl_list); \
sfl != NULL; \
sfl = rcu_dereference(sfl->next))
@ -262,12 +262,11 @@ static struct ip6_flowlabel *fl_intern(struct net *net,
struct ip6_flowlabel *__fl6_sock_lookup(struct sock *sk, __be32 label)
{
struct ipv6_fl_socklist *sfl;
struct ipv6_pinfo *np = inet6_sk(sk);
label &= IPV6_FLOWLABEL_MASK;
rcu_read_lock();
for_each_sk_fl_rcu(np, sfl) {
for_each_sk_fl_rcu(sk, sfl) {
struct ip6_flowlabel *fl = sfl->fl;
if (fl->label == label && atomic_inc_not_zero(&fl->users)) {
@ -283,16 +282,16 @@ EXPORT_SYMBOL_GPL(__fl6_sock_lookup);
void fl6_free_socklist(struct sock *sk)
{
struct ipv6_pinfo *np = inet6_sk(sk);
struct inet_sock *inet = inet_sk(sk);
struct ipv6_fl_socklist *sfl;
if (!rcu_access_pointer(np->ipv6_fl_list))
if (!rcu_access_pointer(inet->ipv6_fl_list))
return;
spin_lock_bh(&ip6_sk_fl_lock);
while ((sfl = rcu_dereference_protected(np->ipv6_fl_list,
while ((sfl = rcu_dereference_protected(inet->ipv6_fl_list,
lockdep_is_held(&ip6_sk_fl_lock))) != NULL) {
np->ipv6_fl_list = sfl->next;
inet->ipv6_fl_list = sfl->next;
spin_unlock_bh(&ip6_sk_fl_lock);
fl_release(sfl->fl);
@ -470,16 +469,15 @@ done:
static int mem_check(struct sock *sk)
{
struct ipv6_pinfo *np = inet6_sk(sk);
struct ipv6_fl_socklist *sfl;
int room = FL_MAX_SIZE - atomic_read(&fl_size);
struct ipv6_fl_socklist *sfl;
int count = 0;
if (room > FL_MAX_SIZE - FL_MAX_PER_SOCK)
return 0;
rcu_read_lock();
for_each_sk_fl_rcu(np, sfl)
for_each_sk_fl_rcu(sk, sfl)
count++;
rcu_read_unlock();
@ -492,13 +490,15 @@ static int mem_check(struct sock *sk)
return 0;
}
static inline void fl_link(struct ipv6_pinfo *np, struct ipv6_fl_socklist *sfl,
struct ip6_flowlabel *fl)
static inline void fl_link(struct sock *sk, struct ipv6_fl_socklist *sfl,
struct ip6_flowlabel *fl)
{
struct inet_sock *inet = inet_sk(sk);
spin_lock_bh(&ip6_sk_fl_lock);
sfl->fl = fl;
sfl->next = np->ipv6_fl_list;
rcu_assign_pointer(np->ipv6_fl_list, sfl);
sfl->next = inet->ipv6_fl_list;
rcu_assign_pointer(inet->ipv6_fl_list, sfl);
spin_unlock_bh(&ip6_sk_fl_lock);
}
@ -520,7 +520,7 @@ int ipv6_flowlabel_opt_get(struct sock *sk, struct in6_flowlabel_req *freq,
rcu_read_lock();
for_each_sk_fl_rcu(np, sfl) {
for_each_sk_fl_rcu(sk, sfl) {
if (sfl->fl->label == (np->flow_label & IPV6_FLOWLABEL_MASK)) {
spin_lock_bh(&ip6_fl_lock);
freq->flr_label = sfl->fl->label;
@ -559,7 +559,7 @@ static int ipv6_flowlabel_put(struct sock *sk, struct in6_flowlabel_req *freq)
}
spin_lock_bh(&ip6_sk_fl_lock);
for (sflp = &np->ipv6_fl_list;
for (sflp = &inet_sk(sk)->ipv6_fl_list;
(sfl = socklist_dereference(*sflp)) != NULL;
sflp = &sfl->next) {
if (sfl->fl->label == freq->flr_label)
@ -579,13 +579,12 @@ found:
static int ipv6_flowlabel_renew(struct sock *sk, struct in6_flowlabel_req *freq)
{
struct ipv6_pinfo *np = inet6_sk(sk);
struct net *net = sock_net(sk);
struct ipv6_fl_socklist *sfl;
int err;
rcu_read_lock();
for_each_sk_fl_rcu(np, sfl) {
for_each_sk_fl_rcu(sk, sfl) {
if (sfl->fl->label == freq->flr_label) {
err = fl6_renew(sfl->fl, freq->flr_linger,
freq->flr_expires);
@ -614,7 +613,6 @@ static int ipv6_flowlabel_get(struct sock *sk, struct in6_flowlabel_req *freq,
{
struct ipv6_fl_socklist *sfl, *sfl1 = NULL;
struct ip6_flowlabel *fl, *fl1 = NULL;
struct ipv6_pinfo *np = inet6_sk(sk);
struct net *net = sock_net(sk);
int err;
@ -645,7 +643,7 @@ static int ipv6_flowlabel_get(struct sock *sk, struct in6_flowlabel_req *freq,
if (freq->flr_label) {
err = -EEXIST;
rcu_read_lock();
for_each_sk_fl_rcu(np, sfl) {
for_each_sk_fl_rcu(sk, sfl) {
if (sfl->fl->label == freq->flr_label) {
if (freq->flr_flags & IPV6_FL_F_EXCL) {
rcu_read_unlock();
@ -682,7 +680,7 @@ recheck:
fl1->linger = fl->linger;
if ((long)(fl->expires - fl1->expires) > 0)
fl1->expires = fl->expires;
fl_link(np, sfl1, fl1);
fl_link(sk, sfl1, fl1);
fl_free(fl);
return 0;
@ -716,7 +714,7 @@ release:
}
}
fl_link(np, sfl1, fl);
fl_link(sk, sfl1, fl);
return 0;
done:
fl_free(fl);

13
net/ipv6/tcp_ipv6.c
View file

@ -1386,7 +1386,9 @@ static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *
if (!newsk)
return NULL;
inet_sk(newsk)->pinet6 = tcp_inet6_sk(newsk);
newinet = inet_sk(newsk);
newinet->pinet6 = tcp_inet6_sk(newsk);
newinet->ipv6_fl_list = NULL;
newnp = tcp_inet6_sk(newsk);
newtp = tcp_sk(newsk);
@ -1405,7 +1407,6 @@ static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *
newnp->ipv6_mc_list = NULL;
newnp->ipv6_ac_list = NULL;
newnp->ipv6_fl_list = NULL;
newnp->pktoptions = NULL;
newnp->opt = NULL;
newnp->mcast_oif = inet_iif(skb);
@ -1453,10 +1454,12 @@ static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *
newsk->sk_gso_type = SKB_GSO_TCPV6;
inet6_sk_rx_dst_set(newsk, skb);
inet_sk(newsk)->pinet6 = tcp_inet6_sk(newsk);
newinet = inet_sk(newsk);
newinet->pinet6 = tcp_inet6_sk(newsk);
newinet->ipv6_fl_list = NULL;
newinet->inet_opt = NULL;
newtp = tcp_sk(newsk);
newinet = inet_sk(newsk);
newnp = tcp_inet6_sk(newsk);
memcpy(newnp, np, sizeof(struct ipv6_pinfo));
@ -1469,10 +1472,8 @@ static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *
First: no IPv4 options.
*/
newinet->inet_opt = NULL;
newnp->ipv6_mc_list = NULL;
newnp->ipv6_ac_list = NULL;
newnp->ipv6_fl_list = NULL;
/* Clone RX bits */
newnp->rxopt.all = np->rxopt.all;

8
net/sctp/ipv6.c
View file

@ -782,9 +782,10 @@ static struct sock *sctp_v6_create_accept_sk(struct sock *sk,
struct sctp_association *asoc,
bool kern)
{
struct sock *newsk;
struct ipv6_pinfo *newnp, *np = inet6_sk(sk);
struct sctp6_sock *newsctp6sk;
struct inet_sock *newinet;
struct sock *newsk;
newsk = sk_alloc(sock_net(sk), PF_INET6, GFP_KERNEL, sk->sk_prot, kern);
if (!newsk)
@ -796,7 +797,9 @@ static struct sock *sctp_v6_create_accept_sk(struct sock *sk,
sock_reset_flag(sk, SOCK_ZAPPED);
newsctp6sk = (struct sctp6_sock *)newsk;
inet_sk(newsk)->pinet6 = &newsctp6sk->inet6;
newinet = inet_sk(newsk);
newinet->pinet6 = &newsctp6sk->inet6;
newinet->ipv6_fl_list = NULL;
sctp_sk(newsk)->v4mapped = sctp_sk(sk)->v4mapped;
@ -805,7 +808,6 @@ static struct sock *sctp_v6_create_accept_sk(struct sock *sk,
memcpy(newnp, np, sizeof(struct ipv6_pinfo));
newnp->ipv6_mc_list = NULL;
newnp->ipv6_ac_list = NULL;
newnp->ipv6_fl_list = NULL;
sctp_v6_copy_ip_options(sk, newsk);