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linux-stable/Documentation/networking/net_cachelines/inet_sock.rst

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Documentations: Analyze heavily used Networking related structs Analyzed a few structs in the networking stack by looking at variables within them that are used in the TCP/IP fast path. Fast path is defined as TCP path where data is transferred from sender to receiver unidirectionally. It doesn't include phases other than TCP_ESTABLISHED, nor does it look at error paths. We hope to re-organizing variables that span many cachelines whose fast path variables are also spread out, and this document can help future developers keep networking fast path cachelines small. Optimized_cacheline field is computed as (Fastpath_Bytes/L3_cacheline_size_x86), and not the actual organized results (see patches to come for these). Investigation is done on 6.5 Name Struct_Cachelines Cur_fastpath_cache Fastpath_Bytes Optimized_cacheline tcp_sock 42 (2664 Bytes) 12 396 8 net_device 39 (2240 bytes) 12 234 4 inet_sock 15 (960 bytes) 14 922 14 Inet_connection_sock 22 (1368 bytes) 18 1166 18 Netns_ipv4 (sysctls) 12 (768 bytes) 4 77 2 linux_mib 16 (1060) 6 104 2 Note how there isn't much improvement space for inet_sock and Inet_connection_sock because sk and icsk_inet respectively takes up so much of the struct that rest of the variables become a small portion of the struct size. So, we decided to reorganize tcp_sock, net_device, netns_ipv4 Suggested-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Coco Li <lixiaoyan@google.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2023-11-29 07:27:52 +00:00
.. SPDX-License-Identifier: GPL-2.0
.. Copyright (C) 2023 Google LLC
Documentations: fix net_cachelines documentation build warning Original errors: Documentation/networking/net_cachelines/index.rst:3: WARNING: Explicit markup ends without a blank line; unexpected unindent. Documentation/networking/net_cachelines/inet_connection_sock.rst:3: WARNING: Explicit markup ends without a blank line; unexpected unindent. Documentation/networking/net_cachelines/inet_sock.rst:3: WARNING: Explicit markup ends without a blank line; unexpected unindent. Documentation/networking/net_cachelines/net_device.rst:3: WARNING: Explicit markup ends without a blank line; unexpected unindent. Documentation/networking/net_cachelines/netns_ipv4_sysctl.rst:3: WARNING: Explicit markup ends without a blank line; unexpected unindent. Documentation/networking/net_cachelines/snmp.rst:3: WARNING: Explicit markup ends without a blank line; unexpected unindent. Documentation/networking/net_cachelines/tcp_sock.rst:3: WARNING: Explicit markup ends without a blank line; unexpected unindent. Fixes: 14006f1d8fa2 ("Documentations: Analyze heavily used Networking related structs") Signed-off-by: Coco Li <lixiaoyan@google.com> Link: https://lore.kernel.org/r/20231204220728.746134-1-lixiaoyan@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-12-04 22:07:28 +00:00
Documentations: Analyze heavily used Networking related structs Analyzed a few structs in the networking stack by looking at variables within them that are used in the TCP/IP fast path. Fast path is defined as TCP path where data is transferred from sender to receiver unidirectionally. It doesn't include phases other than TCP_ESTABLISHED, nor does it look at error paths. We hope to re-organizing variables that span many cachelines whose fast path variables are also spread out, and this document can help future developers keep networking fast path cachelines small. Optimized_cacheline field is computed as (Fastpath_Bytes/L3_cacheline_size_x86), and not the actual organized results (see patches to come for these). Investigation is done on 6.5 Name Struct_Cachelines Cur_fastpath_cache Fastpath_Bytes Optimized_cacheline tcp_sock 42 (2664 Bytes) 12 396 8 net_device 39 (2240 bytes) 12 234 4 inet_sock 15 (960 bytes) 14 922 14 Inet_connection_sock 22 (1368 bytes) 18 1166 18 Netns_ipv4 (sysctls) 12 (768 bytes) 4 77 2 linux_mib 16 (1060) 6 104 2 Note how there isn't much improvement space for inet_sock and Inet_connection_sock because sk and icsk_inet respectively takes up so much of the struct that rest of the variables become a small portion of the struct size. So, we decided to reorganize tcp_sock, net_device, netns_ipv4 Suggested-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Coco Li <lixiaoyan@google.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2023-11-29 07:27:52 +00:00
=====================================================
inet_connection_sock struct fast path usage breakdown
=====================================================
Type Name fastpath_tx_access fastpath_rx_access comment
..struct ..inet_sock
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 - -