netdev - [PATCH net-next 1/2] net: snmp: inline snmp_get_cpu

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Date:   Wed, 29 Sep 2021 18:03:32 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     netdev <netdev@...r.kernel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Eric Dumazet <eric.dumazet@...il.com>,
        Mat Martineau <mathew.j.martineau@...ux.intel.com>,
        Matthieu Baerts <matthieu.baerts@...sares.net>
Subject: [PATCH net-next 1/2] net: snmp: inline snmp_get_cpu_field()

From: Eric Dumazet <edumazet@...gle.com>

This trivial function is called ~90,000 times on 256 cpus hosts,
when reading /proc/net/netstat. And this number keeps inflating.

Inlining it saves many cycles.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 include/net/ip.h   | 6 +++++-
 net/ipv4/af_inet.c | 6 ------
 2 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/include/net/ip.h b/include/net/ip.h
index 9192444f2964ebb59454a7dfa5ddf3b19dea04c9..cf229a53119428307da898af4b0dc23e1cecc053 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -291,7 +291,11 @@ void ip_send_unicast_reply(struct sock *sk, struct sk_buff *skb,
 #define NET_ADD_STATS(net, field, adnd)	SNMP_ADD_STATS((net)->mib.net_statistics, field, adnd)
 #define __NET_ADD_STATS(net, field, adnd) __SNMP_ADD_STATS((net)->mib.net_statistics, field, adnd)
 
-u64 snmp_get_cpu_field(void __percpu *mib, int cpu, int offct);
+static inline u64 snmp_get_cpu_field(void __percpu *mib, int cpu, int offt)
+{
+	return  *(((unsigned long *)per_cpu_ptr(mib, cpu)) + offt);
+}
+
 unsigned long snmp_fold_field(void __percpu *mib, int offt);
 #if BITS_PER_LONG==32
 u64 snmp_get_cpu_field64(void __percpu *mib, int cpu, int offct,
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index 40558033f857c0ca7d98b778f70487e194f3d066..967926c1bf56cfc915258b0969914b11f24c1e16 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -1662,12 +1662,6 @@ int inet_ctl_sock_create(struct sock **sk, unsigned short family,
 }
 EXPORT_SYMBOL_GPL(inet_ctl_sock_create);
 
-u64 snmp_get_cpu_field(void __percpu *mib, int cpu, int offt)
-{
-	return  *(((unsigned long *)per_cpu_ptr(mib, cpu)) + offt);
-}
-EXPORT_SYMBOL_GPL(snmp_get_cpu_field);
-
 unsigned long snmp_fold_field(void __percpu *mib, int offt)
 {
 	unsigned long res = 0;
-- 
2.33.0.800.g4c38ced690-goog