[dpdk-dev] [PATCH v3 3/3] net/failsafe: improve Rx sub-devices iteration

[Gaëtan Rivet]

Hi Matan,

The other commits make sense to me so no issue there.
I'm just surprised by this one so a quick question.

On Tue, Dec 19, 2017 at 05:14:29PM +0000, Matan Azrad wrote:
> Connecting the sub-devices each other by cyclic linked list can help to
> iterate over them by Rx burst functions because there is no need to
> check the sub-devices ring wraparound.
> 
> Create the aforementioned linked-list and change the Rx burst functions
> iteration accordingly.

I'm surprised that a linked-list iteration, with the usual
dereferencing, is better than doing some integer arithmetic.
Maybe the locality of the referenced data helps.

Anyway, were you able to count the cycles gained by this change? It
might be interesting to do a measure with a CPU-bound bench, such as with
a dummy device under the fail-safe (ring or such). MLX devices use a lot
of PCI bandwidth, so the bottleneck could be masked in a physical
setting.

No comments otherwise, if you are sure that this is a performance gain,
the implementation seems ok to me.

Regards,
-- 
Gaëtan Rivet
6WIND