[dpdk-dev] [RFC v3] latencystats: added new library for latency stats

[Pattan, Reshma]

Hi,

The below latency stats RFC adds new field to second cache line of mbuf. This is not an ABI break.
But I would like to emphasize on this  point so you can have a look into the changes and provide comments.

Thanks,
Reshma

> -----Original Message-----
> From: Pattan, Reshma
> Sent: Monday, October 17, 2016 2:40 PM
> To: dev at dpdk.org
> Cc: Pattan, Reshma <reshma.pattan at intel.com>
> Subject: [RFC v3] latencystats: added new library for latency stats
> 
> Library is designed to calculate latency stats and report them to the application
> when queried. Library measures minimum, average, maximum latencies and
> jitter in nano seconds.
> Current implementation supports global latency stats, i.e. per application stats.
> 
> Added new field to mbuf struct to mark the packet arrival time on Rx and use the
> times tamp to measure the latency on Tx.
> 
> Modified dpdk-procinfo process to display the new stats.
> 
> APIs:
> 
> Added APIs to initialize and un initialize latency stats calculation.
> Added API to retrieve latency stats names and values.
> 
> Functionality:
> 
> *Library will register ethdev Rx/Tx callbacks for each active port, queue
> combinations.
> *Library will register latency stats names with new stats library, which is under
> design for now.
> *Rx packets will be marked with time stamp on each sampling interval.
> *On Tx side, packets with time stamp will be considered for calculating the
> minimum, maximum, average latencies and jitter.
> *Average latency is calculated by summing all the latencies measured for each
> time stamped packet and dividing that by total time stamped packets.
> *Minimum and maximum latencies will be low and high latency values observed
> so far.
> *Jitter calculation is done based on inter packet delay variation.
> *Measured stats can be retrieved via get API of the libray (or) by calling generic
> get API of the new stats library, in this case callback is provided to update the
> stats  into new stats library.
> 
> Signed-off-by: Reshma Pattan <reshma.pattan at intel.com>