netfilter: add xt_cpu match

In some situations a CPU match permits a better spreading of
connections, or select targets only for a given cpu.

With Remote Packet Steering or multiqueue NIC and appropriate IRQ
affinities, we can distribute trafic on available cpus, per session.
(all RX packets for a given flow is handled by a given cpu)

Some legacy applications being not SMP friendly, one way to scale a
server is to run multiple copies of them.

Instead of randomly choosing an instance, we can use the cpu number as a
key so that softirq handler for a whole instance is running on a single
cpu, maximizing cache effects in TCP/UDP stacks.

Using NAT for example, a four ways machine might run four copies of
server application, using a separate listening port for each instance,
but still presenting an unique external port :

iptables -t nat -A PREROUTING -p tcp --dport 80 -m cpu --cpu 0 \
        -j REDIRECT --to-port 8080

iptables -t nat -A PREROUTING -p tcp --dport 80 -m cpu --cpu 1 \
        -j REDIRECT --to-port 8081

iptables -t nat -A PREROUTING -p tcp --dport 80 -m cpu --cpu 2 \
        -j REDIRECT --to-port 8082

iptables -t nat -A PREROUTING -p tcp --dport 80 -m cpu --cpu 3 \
        -j REDIRECT --to-port 8083

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
This commit is contained in:
Eric Dumazet 2010-07-23 12:59:36 +02:00 committed by Patrick McHardy
parent 7f1c407579
commit e8648a1fdb
5 changed files with 86 additions and 1 deletions

View file

@ -20,12 +20,13 @@ header-y += xt_TCPMSS.h
header-y += xt_TCPOPTSTRIP.h
header-y += xt_TEE.h
header-y += xt_TPROXY.h
header-y += xt_cluster.h
header-y += xt_comment.h
header-y += xt_connbytes.h
header-y += xt_connlimit.h
header-y += xt_connmark.h
header-y += xt_conntrack.h
header-y += xt_cluster.h
header-y += xt_cpu.h
header-y += xt_dccp.h
header-y += xt_dscp.h
header-y += xt_esp.h

View file

@ -0,0 +1,11 @@
#ifndef _XT_CPU_H
#define _XT_CPU_H
#include <linux/types.h>
struct xt_cpu_info {
__u32 cpu;
__u32 invert;
};
#endif /*_XT_CPU_H*/

View file

@ -663,6 +663,15 @@ config NETFILTER_XT_MATCH_CONNTRACK
To compile it as a module, choose M here. If unsure, say N.
config NETFILTER_XT_MATCH_CPU
tristate '"cpu" match support'
depends on NETFILTER_ADVANCED
help
CPU matching allows you to match packets based on the CPU
currently handling the packet.
To compile it as a module, choose M here. If unsure, say N.
config NETFILTER_XT_MATCH_DCCP
tristate '"dccp" protocol match support'
depends on NETFILTER_ADVANCED

View file

@ -70,6 +70,7 @@ obj-$(CONFIG_NETFILTER_XT_MATCH_COMMENT) += xt_comment.o
obj-$(CONFIG_NETFILTER_XT_MATCH_CONNBYTES) += xt_connbytes.o
obj-$(CONFIG_NETFILTER_XT_MATCH_CONNLIMIT) += xt_connlimit.o
obj-$(CONFIG_NETFILTER_XT_MATCH_CONNTRACK) += xt_conntrack.o
obj-$(CONFIG_NETFILTER_XT_MATCH_CPU) += xt_cpu.o
obj-$(CONFIG_NETFILTER_XT_MATCH_DCCP) += xt_dccp.o
obj-$(CONFIG_NETFILTER_XT_MATCH_DSCP) += xt_dscp.o
obj-$(CONFIG_NETFILTER_XT_MATCH_ESP) += xt_esp.o

63
net/netfilter/xt_cpu.c Normal file
View file

@ -0,0 +1,63 @@
/* Kernel module to match running CPU */
/*
* Might be used to distribute connections on several daemons, if
* RPS (Remote Packet Steering) is enabled or NIC is multiqueue capable,
* each RX queue IRQ affined to one CPU (1:1 mapping)
*
*/
/* (C) 2010 Eric Dumazet
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/netfilter/xt_cpu.h>
#include <linux/netfilter/x_tables.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Eric Dumazet <eric.dumazet@gmail.com>");
MODULE_DESCRIPTION("Xtables: CPU match");
static int cpu_mt_check(const struct xt_mtchk_param *par)
{
const struct xt_cpu_info *info = par->matchinfo;
if (info->invert & ~1)
return -EINVAL;
return 0;
}
static bool cpu_mt(const struct sk_buff *skb, struct xt_action_param *par)
{
const struct xt_cpu_info *info = par->matchinfo;
return (info->cpu == smp_processor_id()) ^ info->invert;
}
static struct xt_match cpu_mt_reg __read_mostly = {
.name = "cpu",
.revision = 0,
.family = NFPROTO_UNSPEC,
.checkentry = cpu_mt_check,
.match = cpu_mt,
.matchsize = sizeof(struct xt_cpu_info),
.me = THIS_MODULE,
};
static int __init cpu_mt_init(void)
{
return xt_register_match(&cpu_mt_reg);
}
static void __exit cpu_mt_exit(void)
{
xt_unregister_match(&cpu_mt_reg);
}
module_init(cpu_mt_init);
module_exit(cpu_mt_exit);