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Merge branch 'net-misplaced-fields'
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Eric Dumazet says:

====================
net: more three misplaced fields

We recently reorganized some structures for better data locality
in networking fast paths.

This series moves three fields that were not correctly classified.

There probably more to come.

Reference : https://lwn.net/Articles/951321/
====================

Signed-off-by: David S. Miller <[email protected]>
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davem330 committed Feb 12, 2024
2 parents 78e563f + c353c7b commit bab091d
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Showing 6 changed files with 16 additions and 14 deletions.
4 changes: 2 additions & 2 deletions Documentation/networking/net_cachelines/net_device.rst
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Expand Up @@ -136,8 +136,8 @@ struct_netpoll_info* npinfo -
possible_net_t nd_net - read_mostly (dev_net)napi_busy_loop,tcp_v(4/6)_rcv,ip(v6)_rcv,ip(6)_input,ip(6)_input_finish
void* ml_priv
enum_netdev_ml_priv_type ml_priv_type
struct_pcpu_lstats__percpu* lstats
struct_pcpu_sw_netstats__percpu* tstats
struct_pcpu_lstats__percpu* lstats read_mostly dev_lstats_add()
struct_pcpu_sw_netstats__percpu* tstats read_mostly dev_sw_netstats_tx_add()
struct_pcpu_dstats__percpu* dstats
struct_garp_port* garp_port
struct_mrp_port* mrp_port
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4 changes: 2 additions & 2 deletions Documentation/networking/net_cachelines/tcp_sock.rst
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Expand Up @@ -38,13 +38,13 @@ u32 max_window read_mostly -
u32 mss_cache read_mostly read_mostly tcp_rate_check_app_limited,tcp_current_mss,tcp_sync_mss,tcp_sndbuf_expand,tcp_tso_should_defer(tx);tcp_update_pacing_rate,tcp_clean_rtx_queue(rx)
u32 window_clamp read_mostly read_write tcp_rcv_space_adjust,__tcp_select_window
u32 rcv_ssthresh read_mostly - __tcp_select_window
u82 scaling_ratio
u8 scaling_ratio read_mostly read_mostly tcp_win_from_space
struct tcp_rack
u16 advmss - read_mostly tcp_rcv_space_adjust
u8 compressed_ack
u8:2 dup_ack_counter
u8:1 tlp_retrans
u8:1 tcp_usec_ts
u8:1 tcp_usec_ts read_mostly read_mostly
u32 chrono_start read_write - tcp_chrono_start/stop(tcp_write_xmit,tcp_cwnd_validate,tcp_send_syn_data)
u32[3] chrono_stat read_write - tcp_chrono_start/stop(tcp_write_xmit,tcp_cwnd_validate,tcp_send_syn_data)
u8:2 chrono_type read_write - tcp_chrono_start/stop(tcp_write_xmit,tcp_cwnd_validate,tcp_send_syn_data)
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10 changes: 5 additions & 5 deletions include/linux/netdevice.h
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Expand Up @@ -2141,6 +2141,11 @@ struct net_device {

/* TXRX read-mostly hotpath */
__cacheline_group_begin(net_device_read_txrx);
union {
struct pcpu_lstats __percpu *lstats;
struct pcpu_sw_netstats __percpu *tstats;
struct pcpu_dstats __percpu *dstats;
};
unsigned int flags;
unsigned short hard_header_len;
netdev_features_t features;
Expand Down Expand Up @@ -2395,11 +2400,6 @@ struct net_device {
enum netdev_ml_priv_type ml_priv_type;

enum netdev_stat_type pcpu_stat_type:8;
union {
struct pcpu_lstats __percpu *lstats;
struct pcpu_sw_netstats __percpu *tstats;
struct pcpu_dstats __percpu *dstats;
};

#if IS_ENABLED(CONFIG_GARP)
struct garp_port __rcu *garp_port;
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6 changes: 3 additions & 3 deletions include/linux/tcp.h
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Expand Up @@ -221,8 +221,10 @@ struct tcp_sock {
u32 lost_out; /* Lost packets */
u32 sacked_out; /* SACK'd packets */
u16 tcp_header_len; /* Bytes of tcp header to send */
u8 scaling_ratio; /* see tcp_win_from_space() */
u8 chrono_type : 2, /* current chronograph type */
repair : 1,
tcp_usec_ts : 1, /* TSval values in usec */
is_sack_reneg:1, /* in recovery from loss with SACK reneg? */
is_cwnd_limited:1;/* forward progress limited by snd_cwnd? */
__cacheline_group_end(tcp_sock_read_txrx);
Expand Down Expand Up @@ -352,7 +354,6 @@ struct tcp_sock {
u32 compressed_ack_rcv_nxt;
struct list_head tsq_node; /* anchor in tsq_tasklet.head list */

u8 scaling_ratio; /* see tcp_win_from_space() */
/* Information of the most recently (s)acked skb */
struct tcp_rack {
u64 mstamp; /* (Re)sent time of the skb */
Expand All @@ -368,8 +369,7 @@ struct tcp_sock {
u8 compressed_ack;
u8 dup_ack_counter:2,
tlp_retrans:1, /* TLP is a retransmission */
tcp_usec_ts:1, /* TSval values in usec */
unused:4;
unused:5;
u8 thin_lto : 1,/* Use linear timeouts for thin streams */
recvmsg_inq : 1,/* Indicate # of bytes in queue upon recvmsg */
fastopen_connect:1, /* FASTOPEN_CONNECT sockopt */
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3 changes: 2 additions & 1 deletion net/core/dev.c
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Expand Up @@ -11652,11 +11652,12 @@ static void __init net_dev_struct_check(void)
CACHELINE_ASSERT_GROUP_SIZE(struct net_device, net_device_read_tx, 160);

/* TXRX read-mostly hotpath */
CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_txrx, lstats);
CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_txrx, flags);
CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_txrx, hard_header_len);
CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_txrx, features);
CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_txrx, ip6_ptr);
CACHELINE_ASSERT_GROUP_SIZE(struct net_device, net_device_read_txrx, 30);
CACHELINE_ASSERT_GROUP_SIZE(struct net_device, net_device_read_txrx, 38);

/* RX read-mostly hotpath */
CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_rx, ptype_specific);
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3 changes: 2 additions & 1 deletion net/ipv4/tcp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -4615,7 +4615,8 @@ static void __init tcp_struct_check(void)
CACHELINE_ASSERT_GROUP_MEMBER(struct tcp_sock, tcp_sock_read_txrx, prr_out);
CACHELINE_ASSERT_GROUP_MEMBER(struct tcp_sock, tcp_sock_read_txrx, lost_out);
CACHELINE_ASSERT_GROUP_MEMBER(struct tcp_sock, tcp_sock_read_txrx, sacked_out);
CACHELINE_ASSERT_GROUP_SIZE(struct tcp_sock, tcp_sock_read_txrx, 31);
CACHELINE_ASSERT_GROUP_MEMBER(struct tcp_sock, tcp_sock_read_txrx, scaling_ratio);
CACHELINE_ASSERT_GROUP_SIZE(struct tcp_sock, tcp_sock_read_txrx, 32);

/* RX read-mostly hotpath cache lines */
CACHELINE_ASSERT_GROUP_MEMBER(struct tcp_sock, tcp_sock_read_rx, copied_seq);
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