mirror of https://github.com/torvalds/linux.git
8 Commits
| Author | SHA1 | Message | Date |
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Eric Dumazet
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ecfea98b7d |
tcp: add net.ipv4.tcp_rcvbuf_low_rtt
This is a follow up of commit |
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Eric Dumazet
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6d5dea6824 |
tcp: tcp_moderate_rcvbuf is only used in rx path
sysctl_tcp_moderate_rcvbuf is only used from tcp_rcvbuf_grow(). Move it to netns_ipv4_read_rx group. Remove various CACHELINE_ASSERT_GROUP_SIZE() from netns_ipv4_struct_check(), as they have no real benefit but cause pain for all changes. Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com> Link: https://patch.msgid.link/20251119084813.3684576-2-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> |
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Eric Dumazet
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1280c26228 |
tcp: add tcp_rto_max_ms sysctl
Previous patch added a TCP_RTO_MAX_MS socket option to tune a TCP socket max RTO value. Many setups prefer to change a per netns sysctl. This patch adds /proc/sys/net/ipv4/tcp_rto_max_ms Its initial value is 120000 (120 seconds). Keep in mind that a decrease of tcp_rto_max_ms means shorter overall timeouts, unless tcp_retries2 sysctl is increased. Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Jason Xing <kerneljasonxing@gmail.com> Reviewed-by: Neal Cardwell <ncardwell@google.com> Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com> Signed-off-by: Paolo Abeni <pabeni@redhat.com> |
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Jakub Sitnicki
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ca6a6f9386 |
tcp: Add sysctl to configure TIME-WAIT reuse delay
Today we have a hardcoded delay of 1 sec before a TIME-WAIT socket can be reused by reopening a connection. This is a safe choice based on an assumption that the other TCP timestamp clock frequency, which is unknown to us, may be as low as 1 Hz (RFC 7323, section 5.4). However, this means that in the presence of short lived connections with an RTT of couple of milliseconds, the time during which a 4-tuple is blocked from reuse can be orders of magnitude longer that the connection lifetime. Combined with a reduced pool of ephemeral ports, when using IP_LOCAL_PORT_RANGE to share an egress IP address between hosts [1], the long TIME-WAIT reuse delay can lead to port exhaustion, where all available 4-tuples are tied up in TIME-WAIT state. Turn the reuse delay into a per-netns setting so that sysadmins can make more aggressive assumptions about remote TCP timestamp clock frequency and shorten the delay in order to allow connections to reincarnate faster. Note that applications can completely bypass the TIME-WAIT delay protection already today by locking the local port with bind() before connecting. Such immediate connection reuse may result in PAWS failing to detect old duplicate segments, leaving us with just the sequence number check as a safety net. This new configurable offers a trade off where the sysadmin can balance between the risk of PAWS detection failing to act versus exhausting ports by having sockets tied up in TIME-WAIT state for too long. [1] https://lpc.events/event/16/contributions/1349/ Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Jason Xing <kerneljasonxing@gmail.com> Link: https://patch.msgid.link/20241209-jakub-krn-909-poc-msec-tw-tstamp-v2-2-66aca0eed03e@cloudflare.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> |
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Eric Dumazet
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d677aebd66 |
tcp: move sysctl_tcp_l3mdev_accept to netns_ipv4_read_rx
sysctl_tcp_l3mdev_accept is read from TCP receive fast path from tcp_v6_early_demux(), __inet6_lookup_established, inet_request_bound_dev_if(). Move it to netns_ipv4_read_rx. Remove the '#ifdef CONFIG_NET_L3_MASTER_DEV' that was guarding its definition. Note this adds a hole of three bytes that could be filled later. Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: David Ahern <dsahern@kernel.org> Cc: Wei Wang <weiwan@google.com> Cc: Coco Li <lixiaoyan@google.com> Link: https://patch.msgid.link/20241010034100.320832-1-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> |
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Donald Hunter
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54b771e6c6 |
doc: net: Fix .rst rendering of net_cachelines pages
The doc pages under /networking/net_cachelines are unreadable because they lack .rst formatting for the tabular text. Add simple table markup and tidy up the table contents: - remove dashes that represent empty cells because they render as bullets and are not needed - replace 'struct_*' with 'struct *' in the first column so that sphinx can render links for any structs that appear in the docs Signed-off-by: Donald Hunter <donald.hunter@gmail.com> Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com> Reviewed-by: Simon Horman <horms@kernel.org> Link: https://patch.msgid.link/20241008165329.45647-1-donald.hunter@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> |
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Coco Li
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19b707c3f2 |
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:
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Coco Li
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14006f1d8f |
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> |