Re: [PATCH] ipv4: Remove fib_hash.

[Eric Dumazet <eric.dumazet@gmail.com>]

Le mardi 01 février 2011 à 15:19 -0800, David Miller a écrit :
> The time has finally come to remove the hash based routing table
> implementation in ipv4.
> 
> FIB Trie is mature, well tested, and I've done an audit of it's code
> to confirm that it implements insert, delete, and lookup with the same
> identical semantics as fib_hash did.
> 
> If there are any semantic differences found in fib_trie, we should
> simply fix them.
> 
> I've placed the trie statistic config option under advanced router
> configuration.
> 
> Signed-off-by: David S. Miller <davem@davemloft.net>
> ---

Hmm... I know having to maintain two implementations is time consuming,
but I know fib_trie is bigger :

# size net/ipv4/fib_*.o
   text	   data	    bss	    dec	    hex	filename
   7252	    120	      0	   7372	   1ccc	net/ipv4/fib_frontend.o
   7279	     16	      4	   7299	   1c83	net/ipv4/fib_hash.o
   1479	      0	      0	   1479	    5c7	net/ipv4/fib_rules.o
   7885	      0	   2080	   9965	   26ed	net/ipv4/fib_semantics.o
  16222	     16	     16	  16254	   3f7e	net/ipv4/fib_trie.o

In my tests, I know that fib_trie is more expensive for typical routing
tables for hosts (no more than a dozen or entries), in latencies
results, mostly because of icache misses, but also dcache ones.

Thanks