Re: [dpdk-dev] DSW eventdev and multi-process DPDK

["Mattias Rönnblom" <mattias.ronnblom@ericsson.com>]

On 2018-12-21 19:34, Venky Venkatesh wrote:
> 
> 
> On 12/21/18, 10:24 AM, "Mattias Rönnblom" <mattias.ronnblom@ericsson.com> wrote:
> 
>      On 2018-12-21 06:13, Venky Venkatesh wrote:
>      > Hi,
>      > We are considering using a multi-process mode of the DPDK with the event generators and consumers being spread across multiple processes (on different cores). We are also considering using the DSW eventdev. Is the DSW designed for such a use case? If so, are there some restrictions and something specific that need to be done to make it work correctly?
>      >
>      
>      The purpose of an event device is to do dynamic load balancing across
>      multiple cores. Using the DPDK multiple-process support, with its
>      requirement of having unique, non-overlapping, core masks works against
>      or even defeats this purpose.
> 
> [VV]: I don’t understand your last sentence. Suppose I am having multiple packet processing processes (each with a single thread and polling a disjoint set of queues) and each linked to DSW. Each process would invoke the enqueue which will be handled by the DSW linked to that process. Will the DSWs across these processes "collaborate" to get load balancing across the processes?
>      

If the processes are to collaborate, and process packets in the same 
pipeline, they will need to share an event device (for example, a DSW 
instance).

However, if you put each of your pipeline stages into a process with a 
single worker thread, you will not leave any room for an event device to 
load balance, since every eventdev queue will have only a single 
consumer linked to it.