tuning for high connection rates

Mike Tancsa mike at sentex.net
Wed Dec 5 14:28:21 PST 2007

At 05:19 PM 12/5/2007, Philipp Wuensche wrote:

>After switching to net.isr.direct=0 and 346609775 good packets later, RX
>overruns haven't increased by one! Thats nice. Still interrupt is using
>up the CPU. I'm not quite sure if polling would help now!?

Polling is helpful to prevent livelock. Not sure if thats happening 
to you.  What firewall (if any) are you using ?  pf used to be a lot 
slower than ipfw.

The Yandex driver is at
but its against RELENG_6 only I think.

Another thing to try is to turn back on Fast Interrupt handling. I 
think its currently disabled.

In if_em.h, try adding

#define EM_FAST_IRQ 1

and then recompile the kernel or just driver.

>We will try disabling TSO to see if anything changes.

If you have TCP in your app, it seems thats the thing to do according 
to the Intel developer.


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