RE: Why is em nic generating interrupts?

> -----Original Message-----
> From: Terry Lambert [mailto:tlambert2_at_mindspring.com]
> Sent: Thursday, October 09, 2003 5:19 PM
> To: Michael O. Boev
> Cc: freebsd-current_at_FreeBSD.ORG
> Subject: Re: Why is em nic generating interrupts?
>
>
> "Michael O. Boev" wrote:
> > I've got a [uniprocessor 5.1-RELEASE] router machine with fxp
> and em nics.
> > I've built my kernel with the following included:
> >
> > options         DEVICE_POLLING
> > options         HZ=2500
> >
> > and enabled polling in /etc/sysctl.conf.
> [ ... ]
> > What's happening? Is polling working in my case?
> > If yes, why is vmstat showing interrupts? I see clearly,
> > that fxp's counter doesn't increase, and em's is constantly growing.
> >
> > Is there anyone who knows for sure that em's polling works?
>
> You may want to ask Luigi; polling is his code.
>
> However, I believe the issue is that polling doesn't start
> until you take an interrupt, and it stops as soon as there is
> no more data to process, and waits for the next interrupt.
>
> If you were to jack your load way up, you would probably see
> an increase in interrupts, then them dropping off dramatically.
To this dare I object, that there is traffic going through this machine,
and fxp0 is NOT generating interrupts, while em IS. So, if the rule above
works, they both have to behave in same ways.
>
> If all else fails, read the source code... 8-).
)) I've tried to, but... had to ask here. So all is left is to ask Luigi and
Intel.
>
> -- Terry
>
--
Best wishes,
[mike_at_tric.tomsk.gov.ru].