From 6648bd7e0e62c0c8c03b15e00c9e7015e232feff Mon Sep 17 00:00:00 2001 From: Alexander Duyck Date: Thu, 21 Jun 2012 13:58:31 +0000 Subject: [PATCH] ipv4: Add sysctl knob to control early socket demux This change is meant to add a control for disabling early socket demux. The main motivation behind this patch is to provide an option to disable the feature as it adds an additional cost to routing that reduces overall throughput by up to 5%. For example one of my systems went from 12.1Mpps to 11.6 after the early socket demux was added. It looks like the reason for the regression is that we are now having to perform two lookups, first the one for an established socket, and then the one for the routing table. By adding this patch and toggling the value for ip_early_demux to 0 I am able to get back to the 12.1Mpps I was previously seeing. [ Move local variables in ip_rcv_finish() down into the basic block in which they are actually used. -DaveM ] Signed-off-by: Alexander Duyck Signed-off-by: David S. Miller --- include/linux/sysctl.h | 1 + include/net/ip.h | 3 +++ kernel/sysctl_binary.c | 2 ++ net/ipv4/ip_input.c | 22 +++++++++++++--------- net/ipv4/sysctl_net_ipv4.c | 7 +++++++ 5 files changed, 26 insertions(+), 9 deletions(-) diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h index c34b4c82b0dc..20825e5f433f 100644 --- a/include/linux/sysctl.h +++ b/include/linux/sysctl.h @@ -425,6 +425,7 @@ enum NET_TCP_ALLOWED_CONG_CONTROL=123, NET_TCP_MAX_SSTHRESH=124, NET_TCP_FRTO_RESPONSE=125, + NET_IPV4_EARLY_DEMUX=126, }; enum { diff --git a/include/net/ip.h b/include/net/ip.h index 83e0619f59d0..50841bd6f10e 100644 --- a/include/net/ip.h +++ b/include/net/ip.h @@ -210,6 +210,9 @@ extern int inet_peer_threshold; extern int inet_peer_minttl; extern int inet_peer_maxttl; +/* From ip_input.c */ +extern int sysctl_ip_early_demux; + /* From ip_output.c */ extern int sysctl_ip_dynaddr; diff --git a/kernel/sysctl_binary.c b/kernel/sysctl_binary.c index a650694883a1..6a3cf8253aae 100644 --- a/kernel/sysctl_binary.c +++ b/kernel/sysctl_binary.c @@ -415,6 +415,8 @@ static const struct bin_table bin_net_ipv4_table[] = { { CTL_INT, NET_IPV4_IPFRAG_SECRET_INTERVAL, "ipfrag_secret_interval" }, /* NET_IPV4_IPFRAG_MAX_DIST "ipfrag_max_dist" no longer used */ + { CTL_INT, NET_IPV4_EARLY_DEMUX, "ip_early_demux" }, + { CTL_INT, 2088 /* NET_IPQ_QMAX */, "ip_queue_maxlen" }, /* NET_TCP_DEFAULT_WIN_SCALE unused */ diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c index 93b092c9a394..bca25179cdb9 100644 --- a/net/ipv4/ip_input.c +++ b/net/ipv4/ip_input.c @@ -313,6 +313,8 @@ drop: return true; } +int sysctl_ip_early_demux __read_mostly = 1; + static int ip_rcv_finish(struct sk_buff *skb) { const struct iphdr *iph = ip_hdr(skb); @@ -323,16 +325,18 @@ static int ip_rcv_finish(struct sk_buff *skb) * how the packet travels inside Linux networking. */ if (skb_dst(skb) == NULL) { - const struct net_protocol *ipprot; - int protocol = iph->protocol; - int err; + int err = -ENOENT; - rcu_read_lock(); - ipprot = rcu_dereference(inet_protos[protocol]); - err = -ENOENT; - if (ipprot && ipprot->early_demux) - err = ipprot->early_demux(skb); - rcu_read_unlock(); + if (sysctl_ip_early_demux) { + const struct net_protocol *ipprot; + int protocol = iph->protocol; + + rcu_read_lock(); + ipprot = rcu_dereference(inet_protos[protocol]); + if (ipprot && ipprot->early_demux) + err = ipprot->early_demux(skb); + rcu_read_unlock(); + } if (err) { err = ip_route_input_noref(skb, iph->daddr, iph->saddr, diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c index ef32956ed655..12aa0c5867c4 100644 --- a/net/ipv4/sysctl_net_ipv4.c +++ b/net/ipv4/sysctl_net_ipv4.c @@ -300,6 +300,13 @@ static struct ctl_table ipv4_table[] = { .mode = 0644, .proc_handler = proc_dointvec }, + { + .procname = "ip_early_demux", + .data = &sysctl_ip_early_demux, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec + }, { .procname = "ip_dynaddr", .data = &sysctl_ip_dynaddr, -- 2.20.1