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authorEric Dumazet <edumazet@google.com>2017-06-07 23:29:12 +0300
committerDavid S. Miller <davem@davemloft.net>2017-06-08 18:26:19 +0300
commit0604475119de5f80dc051a5db055c6a2a75bd542 (patch)
tree292c38e390647ef05fc445510c4d2a89b10b3f2a /net/decnet
parent06fcb3b69fb8699afa04b020d2a95bd6c4c798ac (diff)
downloadlinux-0604475119de5f80dc051a5db055c6a2a75bd542.tar.xz
tcp: add TCPMemoryPressuresChrono counter
DRAM supply shortage and poor memory pressure tracking in TCP stack makes any change in SO_SNDBUF/SO_RCVBUF (or equivalent autotuning limits) and tcp_mem[] quite hazardous. TCPMemoryPressures SNMP counter is an indication of tcp_mem sysctl limits being hit, but only tracking number of transitions. If TCP stack behavior under stress was perfect : 1) It would maintain memory usage close to the limit. 2) Memory pressure state would be entered for short times. We certainly prefer 100 events lasting 10ms compared to one event lasting 200 seconds. This patch adds a new SNMP counter tracking cumulative duration of memory pressure events, given in ms units. $ cat /proc/sys/net/ipv4/tcp_mem 3088 4117 6176 $ grep TCP /proc/net/sockstat TCP: inuse 180 orphan 0 tw 2 alloc 234 mem 4140 $ nstat -n ; sleep 10 ; nstat |grep Pressure TcpExtTCPMemoryPressures 1700 TcpExtTCPMemoryPressuresChrono 5209 v2: Used EXPORT_SYMBOL_GPL() instead of EXPORT_SYMBOL() as David instructed. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/decnet')
-rw-r--r--net/decnet/af_decnet.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/net/decnet/af_decnet.c b/net/decnet/af_decnet.c
index 405483a07efc..73a0399dc7a2 100644
--- a/net/decnet/af_decnet.c
+++ b/net/decnet/af_decnet.c
@@ -447,7 +447,7 @@ static void dn_destruct(struct sock *sk)
dst_release(rcu_dereference_check(sk->sk_dst_cache, 1));
}
-static int dn_memory_pressure;
+static unsigned long dn_memory_pressure;
static void dn_enter_memory_pressure(struct sock *sk)
{