From 0604475119de5f80dc051a5db055c6a2a75bd542 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 7 Jun 2017 13:29:12 -0700 Subject: 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 Signed-off-by: David S. Miller --- include/net/sock.h | 22 ++-------------------- 1 file changed, 2 insertions(+), 20 deletions(-) (limited to 'include/net/sock.h') diff --git a/include/net/sock.h b/include/net/sock.h index 3467d9e89e7d..858891c36f94 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -1080,6 +1080,7 @@ struct proto { bool (*stream_memory_free)(const struct sock *sk); /* Memory pressure */ void (*enter_memory_pressure)(struct sock *sk); + void (*leave_memory_pressure)(struct sock *sk); atomic_long_t *memory_allocated; /* Current allocated memory. */ struct percpu_counter *sockets_allocated; /* Current number of sockets. */ /* @@ -1088,7 +1089,7 @@ struct proto { * All the __sk_mem_schedule() is of this nature: accounting * is strict, actions are advisory and have some latency. */ - int *memory_pressure; + unsigned long *memory_pressure; long *sysctl_mem; int *sysctl_wmem; int *sysctl_rmem; @@ -1193,25 +1194,6 @@ static inline bool sk_under_memory_pressure(const struct sock *sk) return !!*sk->sk_prot->memory_pressure; } -static inline void sk_leave_memory_pressure(struct sock *sk) -{ - int *memory_pressure = sk->sk_prot->memory_pressure; - - if (!memory_pressure) - return; - - if (*memory_pressure) - *memory_pressure = 0; -} - -static inline void sk_enter_memory_pressure(struct sock *sk) -{ - if (!sk->sk_prot->enter_memory_pressure) - return; - - sk->sk_prot->enter_memory_pressure(sk); -} - static inline long sk_memory_allocated(const struct sock *sk) { -- cgit v1.2.3