From: Eric Dumazet Date: Tue, 19 Aug 2025 17:40:30 +0000 (+0000) Subject: net: set net.core.rmem_max and net.core.wmem_max to 4 MB X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=a6d4f25888b83b8300aef28d9ee22765c1cc9b34;p=users%2Fgriffoul%2Flinux.git net: set net.core.rmem_max and net.core.wmem_max to 4 MB SO_RCVBUF and SO_SNDBUF have limited range today, unless distros or system admins change rmem_max and wmem_max. Even iproute2 uses 1 MB SO_RCVBUF which is capped by the kernel. Decouple [rw]mem_max and [rw]mem_default and increase [rw]mem_max to 4 MB. Before: $ sysctl net.core.rmem_default net.core.rmem_max net.core.wmem_default net.core.wmem_max net.core.rmem_default = 212992 net.core.rmem_max = 212992 net.core.wmem_default = 212992 net.core.wmem_max = 212992 After: $ sysctl net.core.rmem_default net.core.rmem_max net.core.wmem_default net.core.wmem_max net.core.rmem_default = 212992 net.core.rmem_max = 4194304 net.core.wmem_default = 212992 net.core.wmem_max = 4194304 Signed-off-by: Eric Dumazet Reviewed-by: Neal Cardwell Link: https://patch.msgid.link/20250819174030.1986278-1-edumazet@google.com Signed-off-by: Jakub Kicinski --- diff --git a/Documentation/admin-guide/sysctl/net.rst b/Documentation/admin-guide/sysctl/net.rst index 7b0c4291c686..2ef50828aff1 100644 --- a/Documentation/admin-guide/sysctl/net.rst +++ b/Documentation/admin-guide/sysctl/net.rst @@ -222,6 +222,8 @@ rmem_max The maximum receive socket buffer size in bytes. +Default: 4194304 + rps_default_mask ---------------- @@ -247,6 +249,8 @@ wmem_max The maximum send socket buffer size in bytes. +Default: 4194304 + message_burst and message_cost ------------------------------ diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst index 43badb338d22..9f5891c9b07b 100644 --- a/Documentation/networking/ip-sysctl.rst +++ b/Documentation/networking/ip-sysctl.rst @@ -209,7 +209,7 @@ neigh/default/unres_qlen_bytes - INTEGER Setting negative value is meaningless and will return error. - Default: SK_WMEM_MAX, (same as net.core.wmem_default). + Default: SK_WMEM_DEFAULT, (same as net.core.wmem_default). Exact value depends on architecture and kernel options, but should be enough to allow queuing 256 packets @@ -805,8 +805,8 @@ tcp_rmem - vector of 3 INTEGERs: min, default, max This value results in initial window of 65535. max: maximal size of receive buffer allowed for automatically - selected receiver buffers for TCP socket. This value does not override - net.core.rmem_max. Calling setsockopt() with SO_RCVBUF disables + selected receiver buffers for TCP socket. + Calling setsockopt() with SO_RCVBUF disables automatic tuning of that socket's receive buffer size, in which case this value is ignored. Default: between 131072 and 32MB, depending on RAM size. diff --git a/include/net/sock.h b/include/net/sock.h index 1c49ea13af4a..63a6a48afb48 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -2970,8 +2970,8 @@ void sk_get_meminfo(const struct sock *sk, u32 *meminfo); */ #define _SK_MEM_PACKETS 256 #define _SK_MEM_OVERHEAD SKB_TRUESIZE(256) -#define SK_WMEM_MAX (_SK_MEM_OVERHEAD * _SK_MEM_PACKETS) -#define SK_RMEM_MAX (_SK_MEM_OVERHEAD * _SK_MEM_PACKETS) +#define SK_WMEM_DEFAULT (_SK_MEM_OVERHEAD * _SK_MEM_PACKETS) +#define SK_RMEM_DEFAULT (_SK_MEM_OVERHEAD * _SK_MEM_PACKETS) extern __u32 sysctl_wmem_max; extern __u32 sysctl_rmem_max; diff --git a/net/core/sock.c b/net/core/sock.c index ab6953d295df..8002ac6293dc 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -281,12 +281,12 @@ static struct lock_class_key af_elock_keys[AF_MAX]; static struct lock_class_key af_kern_callback_keys[AF_MAX]; /* Run time adjustable parameters. */ -__u32 sysctl_wmem_max __read_mostly = SK_WMEM_MAX; +__u32 sysctl_wmem_max __read_mostly = 4 << 20; EXPORT_SYMBOL(sysctl_wmem_max); -__u32 sysctl_rmem_max __read_mostly = SK_RMEM_MAX; +__u32 sysctl_rmem_max __read_mostly = 4 << 20; EXPORT_SYMBOL(sysctl_rmem_max); -__u32 sysctl_wmem_default __read_mostly = SK_WMEM_MAX; -__u32 sysctl_rmem_default __read_mostly = SK_RMEM_MAX; +__u32 sysctl_wmem_default __read_mostly = SK_WMEM_DEFAULT; +__u32 sysctl_rmem_default __read_mostly = SK_RMEM_DEFAULT; DEFINE_STATIC_KEY_FALSE(memalloc_socks_key); EXPORT_SYMBOL_GPL(memalloc_socks_key); diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c index 5cfc1c939673..833f2cf97178 100644 --- a/net/ipv4/arp.c +++ b/net/ipv4/arp.c @@ -170,7 +170,7 @@ struct neigh_table arp_tbl = { [NEIGH_VAR_DELAY_PROBE_TIME] = 5 * HZ, [NEIGH_VAR_INTERVAL_PROBE_TIME_MS] = 5 * HZ, [NEIGH_VAR_GC_STALETIME] = 60 * HZ, - [NEIGH_VAR_QUEUE_LEN_BYTES] = SK_WMEM_MAX, + [NEIGH_VAR_QUEUE_LEN_BYTES] = SK_WMEM_DEFAULT, [NEIGH_VAR_PROXY_QLEN] = 64, [NEIGH_VAR_ANYCAST_DELAY] = 1 * HZ, [NEIGH_VAR_PROXY_DELAY] = (8 * HZ) / 10, diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c index 7d5abb3158ec..57aaa7ae8ac3 100644 --- a/net/ipv6/ndisc.c +++ b/net/ipv6/ndisc.c @@ -130,7 +130,7 @@ struct neigh_table nd_tbl = { [NEIGH_VAR_DELAY_PROBE_TIME] = 5 * HZ, [NEIGH_VAR_INTERVAL_PROBE_TIME_MS] = 5 * HZ, [NEIGH_VAR_GC_STALETIME] = 60 * HZ, - [NEIGH_VAR_QUEUE_LEN_BYTES] = SK_WMEM_MAX, + [NEIGH_VAR_QUEUE_LEN_BYTES] = SK_WMEM_DEFAULT, [NEIGH_VAR_PROXY_QLEN] = 64, [NEIGH_VAR_ANYCAST_DELAY] = 1 * HZ, [NEIGH_VAR_PROXY_DELAY] = (8 * HZ) / 10,