FreeBSD boxes as a 'router'...

[khatfield at socllc.net]

Barney - I would certainly love to see some real evidence to backup such a ridiculous claim.

I agree here as well with Jim. I have a ton of experience with and without. I haven't done enough testing with FreeBSD 9 to state 100% but I can state that extensive testing and filtering traffic (specifically high PPS DDoS traffic) and polling is a requirement in certain situations. 

It should not be required for normal traffic, certainly under 200Mbps but in no way should polling be discounted completely. Tuning Intel NICs works to an extent but offloading everything to the NIC without polling is a sure fire way to live-lock a system in high PPS situations.

So anyway, I stick to my original assessment that it can be iffy depending on volume and scenario but I will also state that throwing polling out completely discounts one of the strengths easily available on FreeBSD. That would be short-sighted, in my opinion.

My recommendation is to use polling if you begin seeing lag or live-lock. In general use it isn't required but I assure you it can be extremely helpful or detrimental. It all depends on the application of the system and the type of workload it has.

-Kevin



On Nov 20, 2012, at 4:49 PM, "Alfred Perlstein" <bright at mu.org> wrote:

> On 11/20/12 2:42 PM, Jim Thompson wrote:
>> On Nov 20, 2012, at 3:52 PM, Barney Cordoba <barney_cordoba at yahoo.com> wrote:
>> 
>>> Anyone who even mentions polling should be discounted altogether. Polling
>>> had value when you couldn't control the interrupt delays; but interrupt
>>> moderation allows you to pace the interrupts any way you like without
>>> the inefficiencies of polling.
>> You're entitled to your opinion, but experimental results have tended to show yours incorrect.
>> 
>> Jim
> Agree with Jim.  If you want pure packet performance you burn a core to run a polling loop.
> 
> -Alfred