Re: [dpdk-dev] [PATCH] examples/multi_process: fix RX packets distribution

[Gregory Etelson <getelson@nvidia.com>]

Hello Anatoly,

..snip..

> b/examples/multi_process/client_server_mp/m
> p_server/main.c
> > @@ -234,7 +234,7 @@
> process_packets(uint32_t port_num
> __rte_unused,
> >               struct rte_mbuf *pkts[], uint16_t
> rx_count)
> >   {
> >       uint16_t i;
> > -     uint8_t client = 0;
> > +     static uint8_t client = 0;
> >
> >       for (i = 0; i < rx_count; i++) {
> >               enqueue_rx_packet(client, pkts[i]);
> >
> 
> Wouldn't that make it global? I don't recall off
> the top of my head if
> the multiprocess app is intended to have
> multiple Rx threads, but if you
> did have two forwarding threads, they would
> effectively both use the
> same `client` value, stepping on top of each
> other. This should probably
> be per-thread?
> 

MP client-server example was not designed as a multi-threaded app.
Server and clients run in a different process and the model allows one server process.
Server allocates a dedicated ring to each client and distributes Rx packets
between rings in round-robin sequence. 
Each ring configured for single producer and single consumer.
Consider an example when server's rte_eth_rx_burst() returns a single packet
on each call. 
Without the patch, the server will ignore all clients with id > 0 and 
assign all Rx packets to rx_ring 0.
Changing process_packets()  `client` variable to static allows unform round-robin
packets distribution between rings.

Regards,
Gregory