[dpdk-dev] Question on the Ring Library

[Sambath Kumar Balasubramanian]

Thanks François-Frédéric. Trying to embark on a small prototype and see the
results. Thanks for the timing data. Really helpful.

Regards,
Sambath


On Wed, Dec 4, 2013 at 12:02 PM, François-Frédéric Ozog <ff at ozog.com> wrote:

> You are welcome !
>
>
>
> Even if you insert packets in batch into a fifo, the mutex is still
> unpredictable. If one pthread_lock costs 1ms, you are going to lose
> packets, regardless of the number of RSS queues and ring sizes… Batching
> comes with another issue: need to flush a batch after a certain timeout if
> you do not have packets. Userland timer resolution is such that you are
> introducing port to port latency quite a lot: DPDK native, you can manage
> to get a 2µs latency (including PCI express), while with batch it may be
> 1ms… You may find smarter algorithms but still you will be an order of
> magnitude higher than DPDK.
>
>
>
> Hope this helps.
>
>
>
> François-Frédéric
>
>
>
> *De :* Sambath Kumar Balasubramanian [mailto:
> sambath.balasubramanian at gmail.com]
> *Envoyé :* mercredi 4 décembre 2013 15:01
> *À :* François-Frédéric Ozog
> *Cc :* dev at dpdk.org
> *Objet :* Re: [dpdk-dev] Question on the Ring Library
>
>
>
> Thanks François-Frédéric. That puts real good perspective on the cost for
> the vent assuming each packet in the fast will result
>
> in an event. If event rate is orders of magnitude less than the packet
> rate, then I guess we can still achieve 10G since the "extra cost" will be
> in the event thread and not in the fast path thread.
>
>
>
> Regards,
>
> Sambath
>