Re: socket can receive order

[Oliver Hartkopp <socketcan@hartkopp.net>]

Hello Daniel,

On 09.09.2015 18:14, Daniel Squires wrote:
> The Hack seems to work, its been a short test of a half hour so far, but
> before it happened reliably after a few seconds.
>
>> On Tue, Sep 8, 2015 at 9:56 AM Oliver Hartkopp <socketcan@hartkopp.net> wrote:
>>>
>>> See http://marc.info/?l=linux-netdev&m=143689694125450&w=2
>>>
>>> If so, please try the 'hack' I suggested on the netdev ML if it fixes your
>>> problem. It might help for the discussion too.

In the referenced posting above I suggested to set

	skb_set_hash(skb, dev->ifindex, PKT_HASH_TYPE_L2);

to create a interface specific hash for the socket buffer.

And then to enable the receive packet steering (RPS) with

	echo f > /sys/class/net/can0/queues/rx-0/rps_cpus

To create a proper patch and description I evaluated some more skb_set_hash() 
parameters and finally discovered that setting the skb hash seems to be 
obsolete ... %-)

Can you confirm that

	echo f > /sys/class/net/can0/queues/rx-0/rps_cpus

already fixes the out-of-order issue even without setting the skb hash?

If so we could give a general recommendation for multi-core CPU system users 
to enable RPS for CAN interfaces by setting the specific sysfs entry.

Regards,
Oliver