How to setup polling on 'bge' interface

Ed Maste emaste at phaedrus.sandvine.ca
Thu Jul 20 02:38:58 UTC 2006


On Tue, Jul 11, 2006 at 04:09:08PM -0300, Marcelo Gardini do Amaral wrote:

> Hi,
> 
> I'm trying to setup polling in my box. [...]
> But I always get some packet loss. 

A few points:

- Polling and SMP are compatible in 6.1.  In fact, they were compatible
  in earlier versions too; basically it's just the compile-time check
  that had to be "fixed."

- You may have to adjust some parameters in the kern.polling sysctl
  tree - specifically, kern.polling.burst_max, kern.polling.each_burst
  and kern.polling.user_frac might need tweaking.

- The polling feedback algorithm does not work very well if your
  workload is focused largely on per-packet tasks (such as routing or
  bridging).  You'll find that there is still idle CPU time at the
  point you start dropping packets.  I have some work in progress to
  address this, but it's not yet committed.

- Polling's major advantage is the avoidance of livelock on UP systems,
  and not improved performance.

What level of traffic are you putting through this box?  Is it routing/
bridging, or an endpoint like a web server?

Ed Maste


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