em(4) hang [Was: Re: igb(4) won't start with "igb0: Could not setup receive structures"]

[Arnaud Lacombe]

Hi,

On Thu, Mar 31, 2011 at 9:51 AM, Arnaud Lacombe <lacombar at gmail.com> wrote:
> Hi
>
> [let's start a new thread :)]
>
> On Wed, Mar 30, 2011 at 2:22 PM, Jack Vogel <jfvogel at gmail.com> wrote:
>> Read the code in HEAD, em_local_timer() has a test of ALL the rx queues and
>> will schedule a task that refreshes mbufs if they are empty. This has
>> exactly the
>> same effect as checking for some interrupt cause, a cause that is not
>> available
>> when using MSIX on 82574, but this approach works for everything.
>>
> ok, it took me a long time to reproduce the issue with em(4) version
> 7.1.9, about 3h rather than a few minutes a month ago and only got
> ~875 allocations failure vs. several thousand before, here are some
> stats:
>
> # sysctl -a | grep missed
> dev.em.0.mac_stats.missed_packets: 1917112
> dev.em.1.mac_stats.missed_packets: 0
> dev.em.2.mac_stats.missed_packets: 0
> dev.em.3.mac_stats.missed_packets: 0
> dev.em.4.mac_stats.missed_packets: 0
> dev.em.5.mac_stats.missed_packets: 0
>
For the record, we had this issue at a customer today; the system was
still using the driver from 7-STABLE. Fortunately, it should just be a
matter of upgrading to the driver from HEAD, which we already know to
be good, to fix the issue.

Regards,
 - Arnaud