path: root/include/linux
diff options
authorEric Dumazet <>2010-07-23 16:15:14 +0200
committerPatrick McHardy <>2010-07-23 16:15:14 +0200
commit2d59208943a3a2a6e0e30b6c84bb8ae80d444cd3 (patch)
tree37672b09c51845f5255185767f0624bf9c09d559 /include/linux
parent59ccf53b9414d998afd6169cb2d6ba0f3c249081 (diff)
extension: add xt_cpu match
Kernel 2.6.36 supports 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 are 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 <> Signed-off-by: Patrick McHardy <>
Diffstat (limited to 'include/linux')
1 files changed, 11 insertions, 0 deletions
diff --git a/include/linux/netfilter/xt_cpu.h b/include/linux/netfilter/xt_cpu.h
new file mode 100644
index 00000000..93c7f11d
--- /dev/null
+++ b/include/linux/netfilter/xt_cpu.h
@@ -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*/