Am Donnerstag, den 26.04.2012, 10:44 -0700 schrieb Alexander Duyck:
> On 04/26/2012 09:16 AM, Julian Stecklina wrote:
> > Am Donnerstag, den 26.04.2012, 08:13 -0700 schrieb Alexander Duyck:
> >> On 04/26/2012 04:39 AM, Julian Stecklina wrote:
> >>> I noticed this, because interrupt throttling seems to have no effect in
> >>> MSI mode or at least I am unable to limit interrupt rate using the
> >>> relevant module flags or ethtool. Can anyone comment on this?
> > [...]
> >> I'll look into the interrupt throttling issue on MSI interrupts and get
> >> back to you.  As far as I know this is supposed to be working.
> > The concrete problem is that I get more then 100k IRQs per second when I
> > saturate the 10G link. Shouldn't the driver automatically switch to bulk
> > mode?
> >
> > Regards, Julian
> >
> The driver should be switching to polling in that case.  What kind of
> traffic generator are you using to saturate the link?

A FreeBSD box with 8 processes doing sendfile to the Linux box in
question. Both are connected back-to-back.

> Also have you tried just statically setting the ITR value using the
> "ethtool -C ethX rx-usecs xxx" command?  If that works then it would
> imply the issue is in the dynamic interrupt throttling logic.  I just

I think ethtool didn't work for me as well.

> noticed there is a bug in the 3.3 kernel that has been fixed in 3.4 that
> could be the reason for the adaptive interrupt moderation issue.  You
> can find the patch on-line at http://patchwork.ozlabs.org/patch/146332/.
> 
> Please test the patch and let us know if it resolves the issue for you. 
> if it does I will see if I can work with Jeff Kirsher to have us submit
> it for the 3.3 stable tree to resolve this issue.

I tried with 3.4.0-rc4 and it works perfectly. I am happy with using the
RC right now, but if the relevant changes to ixgbe end up in the 3.3
series that would be nice. :)

Regards, Julian

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