Freebsd IP Forwarding performance (question, and some info) [7-stable, current, em, smp]

[Ingo Flaschberger]

Dear Paul,

> Opteron 2222 UP mode, no polling
>
>           input          (em0)           output
>  packets  errs      bytes    packets  errs      bytes colls
>  1071020     0   66403248          2     0        404     0

that looks good. (but seems to be near the limit).

> Polling turned on provided better performance on 32 bit, but it gets strange 
> errors on 64 bit..
> Even at low pps I get small amounts of errors, and high pps same thing.. you 
> would think that if
> it got errors at low pps it would get more errors at high pps but that isn't 
> the case..
> Polling on:
> packets  errs      bytes    packets  errs      bytes colls
>   979736   963   60743636          1     0        226     0
>   991838   496   61493960          1     0        178     0
>   996125   460   61759754          1     0        178     0
>   979381   326   60721626          1     0        178     0
>  1022249   379   63379442          1     0        178     0
>   991468   557   61471020          1     0        178     0
>
> lowering pps a little.......
>          input          (em0)           output
>  packets  errs      bytes    packets  errs      bytes colls
>   818688   151   50758660          1     0        226     0
>   837920   179   51951044          1     0        178     0
>   826217   168   51225458          1     0        178     0
>   801017   100   49663058          1     0        178     0
>   761857   287   47235138          1     0        178     0
>
>
> what could cause this?

*) kern.polling.idle_poll enabled?
*) kern.polling.user_frac ?
*) kern.polling.reg_frac ?
*) kern.polling.burst_max ?
*) kern.polling.each_burst ?

Kind regards,
 	Ingo Flaschberger