Alex,
Thanks for the response, I'll attempt to reproduce with a consistent OS
release and re-open the discussion at that time.
Thanks,
Scott Silverman
On Thu, Dec 19, 2013 at 4:52 PM, Alexander Duyck <
alexander.h.du...@intel.com> wrote:
> On 12/19/2013 10:31 AM, Scott Silverman wrote:
> > We have three generations of servers running nearly identical software.
> > Each subscribes to a variety of multicast groups taking in, on average,
> > 200-300Mbps of data.
> >
> > The oldest generation (2x Xeon X5670, SuperMicro 6016T-NTRF, Intel
> > X520-DA2) has no issues handling all the incoming data. (zero
> > rx_no_dma_resources)
> >
> > The middle generation (2x Xeon E5-2670, SuperMicro 6017R-WRF, Intel
> > X520-DA2) and the newest generation (2x Xeon E5-2680v2, SuperMicro
> > 6017R-WRF, Intel X520-DAs) both have issues handling the incoming data
> > (indicated by increasing rx_no_dma_resources counter).
> >
> > The oldest generation of servers is running CentOS5 on a newer kernel
> > (3.4.41), the others are running CentOS6 on the exact same kernel
> (3.4.41).
> >
> > The oldest generation is using ixgbe 3.13.10, the middle generation
> 3.13.10
> > and the newest are on 3.18.7. All machines are using the set_irq_affinity
> > script to spread queue interrupts across available cores. All machines
> are
> > configured with C1 as the maximum C-state and CPU clocks are all steady
> > between 3-3.2Ghz depending on the processor model.
> >
> > On the middle/newer boxes, lowering the number of RSS queues manually
> (i.e.
> > RSS=8,8) seems to help reduce the amount of dropping, but it does not
> > eliminate it.
> >
> > The ring buffer drops do not seem to correlate with data rates, either.
> It
> > does not seem that it is an issue of keeping up. In addition, the boxes
> are
> > not under particularly heavy load. The CPU usage is generally between
> 3-5%
> > and rarely spikes much higher than 15%. The load average is generally
> > around 2.
> >
> > I am at a loss for what else to try to diagnose and/or fix this. In my
> > mind, the newer boxes should have no problem at all keeping up with the
> > older ones.
> >
> > I've attached the output of ethtool -S, one from each generation of
> server.
> >
> >
> >
> > Thanks,
> >
> > Scott Silverman
>
> Scott,
>
> Have you tried running the CentOS5 w/ newer kernel on any of your newer
> servers, or CentOS6 on one of the older ones? I ask because this would
> seem to be the one of the most significant differences between the
> servers that are not dropping frames and those that are. I suspect you
> may have something in the CentOS6 configuration that is responsible for
> the drops that is not present in the CentOS5 configuration. We really
> need to eliminate any OS based issues before we can really even hope to
> start chasing this issue down into the driver and/or device configuration.
>
> Thanks,
>
> Alex
>
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