Socat SO_REUSEPORT test

gistfile1.txt

For server:
=====

for x in {1..10};do detach ./socat -u TCP-LISTEN:50000,reuseport,fork GOPEN:/tmp/socat-$x.log; done 

For client:
======

for x in {1..10};do date +%r | ./socat -u stdio TCP:0.0.0.0:50000; sleep 2s; done

Results:

/tmp/socat-1.log:07:16:18 PM
/tmp/socat-1.log:07:16:24 PM
/tmp/socat-10.log:07:16:08 PM
/tmp/socat-4.log:07:16:14 PM
/tmp/socat-6.log:07:16:06 PM
/tmp/socat-7.log:07:16:16 PM
/tmp/socat-7.log:07:16:22 PM
/tmp/socat-8.log:07:16:10 PM
/tmp/socat-8.log:07:16:12 PM
/tmp/socat-9.log:07:16:20 PM

With hundred concurrent requests (the earlier ones were serialized), you can see

grep . /tmp/socat*.log | cut -d: -f1 | sort | uniq -c
13 /tmp/socat-1.log
11 /tmp/socat-10.log
17 /tmp/socat-2.log
12 /tmp/socat-3.log
9 /tmp/socat-4.log
9 /tmp/socat-5.log
7 /tmp/socat-6.log
15 /tmp/socat-7.log
10 /tmp/socat-8.log
7 /tmp/socat-9.log

The algorithm used for hashing

net_get_random_once(&inet_ehash_secret, sizeof(inet_ehash_secret));

return __inet_ehashfn(laddr, lport, faddr, fport,
              inet_ehash_secret + net_hash_mix(net));



    static inline unsigned int __inet_ehashfn(const __be32 laddr,
                                            const __u16 lport,
                                            const __be32 faddr,
                                            const __be16 fport,
                                            u32 initval)
    {
            return jhash_3words((__force __u32) laddr,
                                (__force __u32) faddr,
                                ((__u32) lport) << 16 | (__force __u32)fport,
                                initval);
    }

http://en.wikipedia.org/wiki/Jenkins_hash_function