[Click] SMP Click - Question Task scheduling

[Ashok Ambati]

Hello,

I am a new user. I am configuring the kernel module to route between 2
interfaces. On a 2-CPU server, I am creating 2 threads - one polling eth0
and transmitting to eth1 and the other polling eth1 and trasmitting to eth0.
I do not understand how each thread switches between the 2 tasks so as to
maintain a balance between the incoming and outgoing packets. For the eth1
-> eth0 path where there is heavy traffic, the queue fronting the
ToDevice(eth0) is overflowing. Am I doing something wrong?

Here is my config -


// Generated by make-ip-conf.pl

// eth0 192.168.200.136 00:04:23:C5:5D:CA

// eth1 9.47.83.136 00:04:23:C5:5D:CB

// Shared IP input path and routing table

ip :: Strip(14)

-> CheckIPHeader(INTERFACES 192.168.200.136/255.255.255.0
9.47.83.136/255.255.255.0)

-> rt :: StaticIPLookup(

192.168.200.136/32 0,

192.168.200.255/32 0,

192.168.200.0/32 0,

9.47.83.136/32 0,

9.47.83.255/32 0,

9.47.83.0/32 0,

192.168.200.0/255.255.255.0 1,

9.47.83.0/255.255.255.0 2,

255.255.255.255/32 0.0.0.0 0,

0.0.0.0/32 0,

0.0.0.0/0.0.0.0 9.47.83.1 2);

// ARP responses are copied to each ARPQuerier and the host.

arpt :: Tee(3);

// Input and output paths for eth0

c0 :: Classifier(12/0806 20/0001, 12/0806 20/0002, 12/0800, -);

pd0 :: PollDevice(eth0);

todevice0 :: ToDevice(eth0, 8);

pd0 -> c0;

out0 :: Queue(2000) -> todevice0;

c0[0] -> ar0 :: ARPResponder(192.168.200.136/24 00:04:23:C5:5D:CA) -> out0;

arpq0 :: ARPQuerier(192.168.200.136, 00:04:23:C5:5D:CA) -> out0;

c0[1] -> arpt;

arpt[0] -> [1]arpq0;

c0[2] -> Paint(1) -> ip;

c0[3] -> Print("eth0 non-IP") -> Discard;

// Input and output paths for eth1

c1 :: Classifier(12/0806 20/0001, 12/0806 20/0002, 12/0800, -);

pd1 :: PollDevice(eth1);

pd1 -> c1;

todevice1 :: ToDevice(eth1, 8);

out1 :: Queue(2000) -> todevice1;

c1[0] -> ar1 :: ARPResponder(9.47.83.136/24 00:04:23:C5:5D:CB) -> out1;

arpq1 :: ARPQuerier(9.47.83.136, 00:04:23:C5:5D:CB) -> out1;

c1[1] -> arpt;

arpt[1] -> [1]arpq1;

c1[2] -> Paint(2) -> ip;

c1[3] -> Print("eth1 non-IP") -> Discard;

// Local delivery

toh :: ToHost;

arpt[2] -> toh;

rt[0] -> EtherEncap(0x0800, 1:1:1:1:1:1, 2:2:2:2:2:2) -> toh;

// Forwarding path for eth0

rt[1] -> DropBroadcasts

-> cp0 :: PaintTee(1)

-> gio0 :: IPGWOptions(192.168.200.136)

-> FixIPSrc(192.168.200.136)

-> dt0 :: DecIPTTL

-> fr0 :: IPFragmenter(1500)

-> [0]arpq0;

dt0[1] -> ICMPError(192.168.200.136, timeexceeded) -> rt;

fr0[1] -> ICMPError(192.168.200.136, unreachable, needfrag) -> rt;

gio0[1] -> ICMPError(192.168.200.136, parameterproblem) -> rt;

cp0[1] -> ICMPError(192.168.200.136, redirect, host) -> rt;

// Forwarding path for eth1

rt[2] -> DropBroadcasts

-> cp1 :: PaintTee(2)

-> gio1 :: IPGWOptions(9.47.83.136)

-> FixIPSrc(9.47.83.136)

-> dt1 :: DecIPTTL

-> fr1 :: IPFragmenter(1500)

-> [0]arpq1;

dt1[1] -> ICMPError(9.47.83.136, timeexceeded) -> rt;

fr1[1] -> ICMPError(9.47.83.136, unreachable, needfrag) -> rt;

gio1[1] -> ICMPError(9.47.83.136, parameterproblem) -> rt;

cp1[1] -> ICMPError(9.47.83.136, redirect, host) -> rt;

//CPU assignment for Polling and Target devices

StaticThreadSched(pd0 0);

StaticThreadSched(todevice0 1);

StaticThreadSched(pd1 1);

StaticThreadSched(todevice1 0);

// ThreadMonitor();

Thanks.



Ashok.