From 2d59208943a3a2a6e0e30b6c84bb8ae80d444cd3 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 23 Jul 2010 16:15:14 +0200 Subject: 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 --- extensions/libxt_cpu.man | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) create mode 100644 extensions/libxt_cpu.man (limited to 'extensions/libxt_cpu.man') diff --git a/extensions/libxt_cpu.man b/extensions/libxt_cpu.man new file mode 100644 index 00000000..f42ac7a5 --- /dev/null +++ b/extensions/libxt_cpu.man @@ -0,0 +1,16 @@ +.TP +[\fB!\fP] \fB\-\-cpu\fP \fInumber\fP + +Match cpu handling this packet. cpus are numbered from 0 to NR_CPUS-1 +Can be used in combination with RPS (Remote Packet Steering) or +multiqueue NICS to spread network traffic on different queues. +.PP +Example: +.PP +iptables \-t nat \-A PREROUTING \-p tcp \-\-dport 80 \-m cpu \-\-cpu 0 + \-j REDIRECT \-\-to\-port 8080 +.PP +iptables \-t nat \-A PREROUTING \-p tcp \-\-dport 80 \-m cpu \-\-cpu 1 + \-j REDIRECT \-\-to\-port 8081 +.PP +Available since linux 2.6.36 -- cgit v1.2.3