pipe buckets/hash_size

rihad rihad at mail.ru
Tue Dec 11 03:53:29 PST 2007


In FreeBSD 7.0 the defaults are:

net.inet.ip.dummynet.hash_size: Default hash table size
net.inet.ip.dummynet.hash_size: 64

net.inet.ip.dummynet.max_chain_len: Max ratio between dynamic queues and 
net.inet.ip.dummynet.max_chain_len: 16

 From man ipfw: "Target value for the maximum number of pipes/queues in 
a hash bucket. The product max_chain_len*hash_size is used to determine 
the threshold over which empty pipes/queues will be expired even when 

Does hash_size=64 and max_chain_len=16 mean there can only be 64*16 
pipes? hash_size can be as large as 65536. Should I change their values 
so that the product is as large as the expected number of concurrent pipes?

What happens when a pipe expires? Will it get deleted? What if more 
traffic appears triggering the pipe from its original ipfw rule?

Thank you.

More information about the freebsd-net mailing list