[CFT] ipfw SMP-ready dynamic states

[Alfred Perlstein]

Alexander, this is awesome.

On 11/13/12 11:28 AM, Alexander V. Chernikov wrote:
> Hello list!
>
> Currently most ipfw operations with dynamic states (keep-state, 
> check-state, limit) are serialized via IPFW_DYN_LOCK() which is 
> per-vnet mutex lock.
>
> As a result, performance is limited to the same ~650kpps as in routing
> (in several cases).
>
> Patch changes the following:
> * global lock is changed to per-bucket mutex
> * state expiration is done in ipfw_tick every 1s. No expiration is 
> done on forwarding path
> * hash table resize is done automatically and does not cause all 
> states to be lost
>
> The only (architectural) problem I see is unlocked V_dyn_count 
> increments.
> So, we can do the following:
> 1) lock increments/decrements via some separate mutex
> 2) do nothing
> 3) take some combined approach:
>
> Generally, we don't need value to be _exact_.
> As a result, we count total number of states in every ipfw_tick run 
> and set V_dyn_count to new value. New states still increment 
> V_dyn_count unlocked.
>
What about using per-cpu PCPU counters, and then collecting them for 
display/reporting?

-Alfred


>
> Performance:
>
> Synthetic traffic, ipfw with single allow ip from any to any rule: 2.4M.
> single keep-state ip from any to any: 2.2M.
>
> Some more tests should be taken (with large number of states, 
> different types of traffic, etc), maybe I can do some next week.
>
>
> You need to run recent -current or merge r242631 and r242834 before 
> applying this patch.
>
>
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