> On Sep 11, 2018, at 8:28 PM, Sebastian Moeller <[email protected]> wrote:
>>
>> Yeah, good point, I left nat there because I had one port configured for
>> routing and the other for the bridge and was sometimes swapping between the
>> two. I realize now I actually sent the numbers for routing, not bridging.
>> Bridging without ‘nat’ looks a bit higher (155 Mbit for cake instead of 135
>> Mbit). I would re-do all these tests for completeness but I’m out of time
>> now.
>
> Ouch, a ten percent bandwidth cost for the nat feature certainly
> answeers the question whether nat should be the default…
That probably has a lot to do with routing vs bridging though also. If I turn
QoS off, the ER-X does about 250Mbit when routing and 280Mbit with the soft
bridge, so that’s probably most of that difference. I’m not seeing a throughput
difference above random noise between ‘nat’ and ‘nonat’. When I benchmarked it
before I saw an ~1.5% CPU difference, not nothing.
>>> The last time we discussed the bust issue, I could not manage to see
>>> any difference with or without a specified burst, but I strongly believe I
>>> simply did not properly test. Btw, this is unidirectional shaping or with
>>> bidirectional saturation?
>>
>> Unidirectional. I definitely see a difference, but I wonder what criteria we
>> (and I) used for “out of CPU’ in the past.
>
> So totally unscientifically me yardstick was as long as throughput
> increases more or less linearly with configured shaper bandwidth things are
> fine, and then at the candidate bandwidths I ran "top -d 1" and monitored
> both idle% ad sirq% with idle falling below 5% being a strong indicator of
> bottlenecking on cpu cycles. Dlakelan over at github
> (https://github.com/dlakelan/routerperf
> <https://github.com/dlakelan/routerperf>) is working on a small side project
> that aims for tighter multi-core aware logging of cpu usage on a router, but
> that has not left the early prototype stage.
Ok, my frustration with the testing has also been variable results from run to
run. My inner self is saying, yes, do some testing, but don’t spend too much
time on it when it has this stochastic side to it.
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