From b66e91ccbc34ebd5a2f90f9e1bc1597e2924a500 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 15 May 2015 12:39:30 -0700 Subject: [PATCH] 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 Signed-off-by: David S. Miller --- net/ipv4/tcp.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 9eabfd3e0925..c724195e5862 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -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) -- 2.20.1