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 <edumazet@google.com>
Reviewed-by: Neal Cardwell <ncardwell@google.com>
Link: https://patch.msgid.link/20250819174030.1986278-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/Documentation/admin-guide/sysctl/net.rst b/Documentation/admin-guide/sysctl/net.rst
index 7b0c4291c6861e5694c36f89ddbb19d0397e4190..2ef50828aff16b01baf32f5ded9b75a6e699b184 100644 (file)
--- 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 43badb338d22b31dbdaa148cd97a9d21459b86fd..9f5891c9b07b03e975ac80a0523928f22efa1f4a 100644 (file)
--- 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 1c49ea13af4ab2103e85b472af88659a6b27696c..63a6a48afb48ad31abf05f5108886bac9831842a 100644 (file)
--- 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 ab6953d295dfa903e059c654a7917fefb18aa41e..8002ac6293dcac694962be139eadfa6346b72d5b 100644 (file)
--- 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 5cfc1c9396732171b79ce0aac2b0ee11ddfcbd05..833f2cf97178ee6a50fb3c99d02ed5b17ab5a879 100644 (file)
--- 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 7d5abb3158ec9640a45d4f36fbbfdfce070c0dd0..57aaa7ae8ac3109d808dd46e8cfe54b57e48b214 100644 (file)
--- 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,