Re: [dpdk-dev] [RFC PATCHv2 0/2] pktdev as wrapper type

[Bruce Richardson <bruce.richardson@intel.com>]

On Mon, May 11, 2015 at 05:29:39PM +0100, Bruce Richardson wrote:
> Hi all,
> 
> after a small amount of offline discussion with Marc Sune, here is an
> alternative proposal for a higher-level interface - aka pktdev - to allow a
> common Rx/Tx API across device types handling mbufs [for now, ethdev, ring
> and KNI]. The key code is in the first patch fo the set - the second is an
> example of a trivial usecase.
> 
> What is different about this to previously:
> * wrapper class, so no changes to any existing ring, ethdev implementations
> * use of function pointers for RX/TX with an API that maps to ethdev
>   - this means there is little/no additional overhead for ethdev calls
>   - inline special case for rings, to accelerate that. Since we are at a 
>     higher level, we can special case process some things if appropriate. This
>     means the impact to ring ops is one (predictable) branch per burst
> * elimination of the queue abstraction. For the ring and KNI, there is no
>   concept of queues, so we just wrap the functions directly (no need even for
>   wrapper functions, the api's match so we can call directly). This also
>   means:
>   - adding in features per-queue, is far easier as we don't need to worry about
>     having arrays of multiple queues. For example:
>   - adding in buffering on TX (or RX) is easier since again we only have a 
>     single queue.
> * thread safety is made easier using a wrapper. For a MP ring, we can create
>   multiple pktdevs around it, and each thread will then be able to use their
>   own copy, with their own buffering etc.
> 
> However, at this point, I'm just looking for general feedback on this as an
> approach. I think it's quite flexible - even more so than the earlier proposal
> we had. It's less proscriptive and doesn't make any demands on any other libs.
> 
> Comments/thoughts welcome.
> 
> Bruce Richardson (2):
>   Add example pktdev implementation
>   example app showing pktdevs used in a chain
>

Any comments on this RFC before I see about investing further time in it to clean
it up a bit and submit as a non-RFC patchset for merge in 2.1?

/Bruce