Re: [RFC] NAPI as kobject proposal

David Daney
2010-02-03T21:54:28Z

Ben Hutchings wrote:
> On Fri, 2010-01-29 at 10:18 -0800, Stephen Hemminger wrote:
>> The NAPI interface structure in current kernels is managed by the driver.
>> As part of receive packet steering there is a requirement to add an
>> additional parameter to this for the CPU map. And this map needs to
>> have an API to set it.
>>
>> The right way to do this in the kernel model is to make NAPI into
>> a kobject and associate it back with the network device (parent).
>> This isn't wildly difficult but does change some of the API for
>> network device drivers because:
>> 1. They need to handle another possible error on setup
>> 2. NAPI object needs to be dynamically allocated
>> separately (not as part of netdev_priv)
>> 3. Driver should pass index that can be uses as part of
>> name (easier than scanning)
>>
>> Eventually, there will be:
>> /sys/class/net/eth0/napi0/
>> weight
>> cpumap
>
> I think the NAPI objects should be created as children of a bus device
> and then linked from the net device directories, e.g.
>
> /sys/devices/.../ net/eth0/
> napi0 -> ../../napi/napi0
> eth1/
> napi0 -> ../../napi/napi0
> napi/napi0/
> weight
> cpumap
>

This seems right.

Some drivers have a single napi object logically associated with
multiple interfaces. Although the current architecture forces us to
associate the napi object with a single net_device, it would be nice to
move towards something that allows sharing a napi object between
multiple devices.

David Daney