Re: [PATCH 0/9] staging: octeon: multi rx group (queue) support

[David Daney]

On 08/31/2016 08:06 AM, Aaro Koskinen wrote:
> Hi,
>
> On Tue, Aug 30, 2016 at 06:12:17PM -0700, Ed Swierk wrote:
> > On Tue, Aug 30, 2016 at 11:47 AM, Aaro Koskinen <aaro.koskinen@xxxxxx> wrote:
> > > This series implements multiple RX group support that should improve
> > > the networking performance on multi-core OCTEONs. Basically we register
> > > IRQ and NAPI for each group, and ask the HW to select the group for
> > > the incoming packets based on hash.
> > >
> > > Tested on EdgeRouter Lite with a simple forwarding test using two flows
> > > and 16 RX groups distributed between two cores - the routing throughput
> > > is roughly doubled.
> >
> > I applied the series to my 4.4.19 tree, which involved backporting a
> > bunch of other patches from master, most of them trivial.
> >
> > When I test it on a Cavium Octeon 2 (CN6880) board, I get an immediate
> > crash (bus error) in the netif_receive_skb() call from cvm_oct_poll().
> > Replacing the rx_group argument to cvm_oct_poll() with int group, and
> > dereferencing rx_group->group in the caller (cvm_oct_napi_poll())
> > instead makes the crash disappear. Apparently there's some race in
> > dereferencing rx_group from within cvm_oct_poll().
> >
> > With this workaround in place, I can send and receive on XAUI
> > interfaces, but don't see any performance improvement. I'm guessing I
> > need to set receive_group_order > 0. But any value between 1 and 4
> > seems to break rx altogether. When I ping another host I see both
> > request and response on the wire, and the interface counters increase,
> > but the response doesn't make it back to ping.
>
> This happens only on CN68XX, and I found the root cause.
>
> I will send a new series later today.

Thanks,

cn68xx does have a slightly different SSO and interrupt implementation, 
so it will probably need some special case code to handle both styles of 
hardware.

David.

> A.