Commit 49445667 authored Dec 14, 2023 by Eric Dumazet Committed by David S. Miller Dec 15, 2023

net: increase optmem_max default value



For many years, /proc/sys/net/core/optmem_max default value
on a 64bit kernel has been 20 KB.

Regular usage of TCP tx zerocopy needs a bit more.

Google has used 128KB as the default value for 7 years without
any problem.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent e16064c9

Documentation/admin-guide/sysctl/net.rst

+4 −1

Original line number	Diff line number	Diff line
		@@ -345,7 +345,10 @@ optmem_max
		----------

		Maximum ancillary buffer size allowed per socket. Ancillary data is a sequence
		of struct cmsghdr structures with appended data.
		of struct cmsghdr structures with appended data. TCP tx zerocopy also uses
		optmem_max as a limit for its internal structures.

		Default : 128 KB

		fb_tunnels_only_for_init_net
		----------------------------

net/core/sock.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -283,8 +283,10 @@ EXPORT_SYMBOL(sysctl_rmem_max);
		__u32 sysctl_wmem_default __read_mostly = SK_WMEM_MAX;
		__u32 sysctl_rmem_default __read_mostly = SK_RMEM_MAX;

		/* Maximal space eaten by iovec or ancillary data plus some space */
		int sysctl_optmem_max __read_mostly = sizeof(unsigned long)(2UIO_MAXIOV+512);
		/* Limits per socket sk_omem_alloc usage.
		* TCP zerocopy regular usage needs 128 KB.
		*/
		int sysctl_optmem_max __read_mostly = 128 * 1024;
		EXPORT_SYMBOL(sysctl_optmem_max);

		int sysctl_tstamp_allow_data __read_mostly = 1;