Device polling, with SMP?
Don Bowman
don at sandvine.com
Thu Nov 20 09:59:04 PST 2003
From: Avleen Vig [mailto:lists-freebsd at silverwraith.com]
>
> Has anyone here used DEVICE_POLLING on an SMP box?
> I have one server which does recieve ~130kpps at times on an
> interface,
> but I cannot enable DEVICE_POLLING because hte system locks up under
> load from interrupts.
>
> In this case I'm not sure which is better, disabling one of the CPU's,
> or trying to make DECIVE_POLLING work with SMP.
>
> I read Luigi's paper at info.iet.unipi.it/~luigi/polling/ which at the
> end implies that DEVICE_POLLING on an SMP box might not make
> sense - but
> right now for me it would make sense as both CPU's are locked:
> One tries to handle interrupts
> The other tries to manage the application
>
> I could try forcing DEVICE_POLLING to compile as is suggested in that
> URL but I wanted to see if anyone had tried this before.
>
> The interface is an FXP.
We use it on em. I just commented out the #error line that
says you can't do it.
device polling in idle doesn't work, and the user/system time
calculation isn't correct, but it works well otherwise.
--don
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