Commit b66e91cc authored May 15, 2015 by Eric Dumazet Committed by David S. Miller May 17, 2015

tcp: halves tcp_mem[] limits



Allowing tcp to use ~19% of physical memory is way too much,
and allowed bugs to be hidden. Add to this that some drivers use a full
page per incoming frame, so real cost can be twice the advertized one.

Reduce tcp_mem by 50 % as a first step to sanity.

tcp_mem[0,1,2] defaults are now 4.68%, 6.25%, 9.37% of physical memory.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 76dfa608

net/ipv4/tcp.c

+5 −4

Original line number	Diff line number	Diff line
		@@ -3068,11 +3068,12 @@ __setup("thash_entries=", set_thash_entries);

		static void __init tcp_init_mem(void)
		{
		unsigned long limit = nr_free_buffer_pages() / 8;
		unsigned long limit = nr_free_buffer_pages() / 16;

		limit = max(limit, 128UL);
		sysctl_tcp_mem[0] = limit / 4 * 3;
		sysctl_tcp_mem[1] = limit;
		sysctl_tcp_mem[2] = sysctl_tcp_mem[0] * 2;
		sysctl_tcp_mem[0] = limit / 4 * 3; /* 4.68 % */
		sysctl_tcp_mem[1] = limit; /* 6.25 % */
		sysctl_tcp_mem[2] = sysctl_tcp_mem[0] * 2; /* 9.37 % */
		}

		void __init tcp_init(void)

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