[dpdk-dev] Defaults for rte_hash
Matthew Hall
mhall at mhcomputing.net
Tue Sep 9 12:31:53 CEST 2014
Hello,
I was looking at the code which inits rte_hash objects in examples/l3fwd. It's
using approx. 1M to 4M hash 'entries' depending on 32-bit vs 64-bit, but it's
setting the 'bucket_entries' to just 4.
Normally I'm used to using somewhat deeper hash buckets than that... it seems
like having a zillion little tiny hash buckets would cause more TLB pressure
and memory overhead... or does 4 get shifted / exponentiated into 2**4 ?
The documentation in http://dpdk.org/doc/api/structrte__hash__parameters.html
and http://dpdk.org/doc/api/rte__hash_8h.html isn't that clear... is there a
better place to look for this?
In my case I'm looking to create a table of 4M or 8M entries, containing
tables of security threat IPs / domains, to be detected in the traffic. So it
would be good to have some understanding how not to waste a ton of memory on a
table this huge without making it run super slow either.
Did anybody have some experience with how to get this right?
Another thing... the LPM table uses 16-bit Hop IDs. But I would probably have
more than 64K CIDR blocks of badness on the Internet available to me for
analysis. How would I cope with this, besides just letting some attackers
escape unnoticed? ;)
Have we got some kind of structure which allows a greater number of CIDRs even
if it's not quite as fast?
Thanks,
Matthew.
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