e8648a1fdb
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>
64 lines
1.5 KiB
C
64 lines
1.5 KiB
C
/* Kernel module to match running CPU */
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/*
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* Might be used to distribute connections on several daemons, if
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* RPS (Remote Packet Steering) is enabled or NIC is multiqueue capable,
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* each RX queue IRQ affined to one CPU (1:1 mapping)
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*
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*/
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/* (C) 2010 Eric Dumazet
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/module.h>
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#include <linux/skbuff.h>
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#include <linux/netfilter/xt_cpu.h>
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#include <linux/netfilter/x_tables.h>
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Eric Dumazet <eric.dumazet@gmail.com>");
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MODULE_DESCRIPTION("Xtables: CPU match");
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static int cpu_mt_check(const struct xt_mtchk_param *par)
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{
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const struct xt_cpu_info *info = par->matchinfo;
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if (info->invert & ~1)
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return -EINVAL;
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return 0;
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}
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static bool cpu_mt(const struct sk_buff *skb, struct xt_action_param *par)
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{
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const struct xt_cpu_info *info = par->matchinfo;
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return (info->cpu == smp_processor_id()) ^ info->invert;
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}
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static struct xt_match cpu_mt_reg __read_mostly = {
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.name = "cpu",
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.revision = 0,
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.family = NFPROTO_UNSPEC,
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.checkentry = cpu_mt_check,
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.match = cpu_mt,
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.matchsize = sizeof(struct xt_cpu_info),
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.me = THIS_MODULE,
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};
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static int __init cpu_mt_init(void)
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{
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return xt_register_match(&cpu_mt_reg);
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}
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static void __exit cpu_mt_exit(void)
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{
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xt_unregister_match(&cpu_mt_reg);
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}
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module_init(cpu_mt_init);
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module_exit(cpu_mt_exit);
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