svn commit: r336221 - head/sys/net

[Kristof Provost]

On 4 Aug 2018, at 1:04, Gleb Smirnoff wrote:
> On Thu, Jul 12, 2018 at 04:35:35PM +0000, Kristof Provost wrote:
> K> Author: kp
> K> Date: Thu Jul 12 16:35:35 2018
> K> New Revision: 336221
> K> URL: https://svnweb.freebsd.org/changeset/base/336221
> K>
> K> Log:
> K>   pf: Increate default state table size
> K>
> K>   The typical system now has a lot more memory than when pf was 
> new, and is also
> K>   expected to handle more connections. Increase the default size of 
> the state
> K>   table.
> K>   Note that users can overrule this using 'set limit states' in 
> pf.conf.
> K>
> K>   From OpenBSD:
> K>       The year is 2018.
> K>       Mercury, Bowie, Cash, Motorola and DEC all left us.
> K>       Just pf still has a default state table limit of 10000.
> K>       Had! Now it's a tiny little bit more, 100k.
> K>       lead guitar: me
> K>       ok chorus: phessler theo claudio benno
> K>       background school girl laughing: bob
>
> For FreeBSD it would also make sense to bump hash sizes along with 
> this change.
>
Yeah, Olivier did some benchmarking work around this:
https://github.com/ocochard/netbenches/blob/master/Atom_C2758_8Cores-Chelsio_T540-CR/pf-states_hashsize/results/fbsd12-head.r332390/README.md

He found a roughly 10% increase in throughput by increasing the hash 
size to 256K.
I’ve been thinking about making the hash size dynamically configurable 
(so we could calculate it based in the state limit, rather than expect 
users to tune this manually), but that’s probably not going to get 
done any time soon.

I’ll see about increasing the default (although perhaps not to 256K, 
because if my math is right that’s cost us ~20MB of memory) soon, 
because that’s mostly a quick win.

Regards,
Kristof