Re: [dpdk-dev] Please any one who can help me with librte_sched

["Dumitrescu, Cristian" <cristian.dumitrescu@intel.com>]

Hi Ariel,

What's wrong with calling rte_sched_subport_config() and rte_sched_pipe_config() during run-time?

This assumes that:

1. Port initialization is done, which includes the following:
a) the number of subports, pipes per subport are fixed
b) the queues are all created and their size is fixed
c) the pipe profiles are defined
d) Basically the maximal data structures get created (maximum number of supports, pipes and queues) with no run-time changes allowed, apart for the bandwidth related parameters. Queues that do not receive packets are not used now, they will be used as soon as they get packets. The packets-to-queues mapping logic can change over time, as well as the level of activity for different users/queues.

2. The CPU core calling the subport/pipe config functions is the same as the core doing enque/dequeue for this port (for thread safety reasons).
a) As you say, the management core can send update requests to the core running the scheduler, with the latter sampling the request queue regularly and performing the updates.

Regards,
Cristian


-----Original Message-----
From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Stephen Hemminger
Sent: Tuesday, May 27, 2014 5:35 PM
To: Ariel Rodriguez
Cc: dev@dpdk.org
Subject: Re: [dpdk-dev] Please any one who can help me with librte_sched

On Tue, 27 May 2014 10:33:02 -0300
Ariel Rodriguez <arodriguez@callistech.com> wrote:

> Hello , this is my third mail , the previous mails have not been answered
> yet.
> 
> I justo need someone explains to me  how the librte_sched framework behaves
> in a specific situation.
> 
> I have a managment application , this connects with a ring with the tx
> core, when a user applies some configuration of the bandwith mangement ,
> the tx core read the message in the ring parse the configuration in a
> rte_port_params struct , subport_params and pipe_params, then creates a new
> rte_sched from scratch , and then changes the pointer of the current
> rte_sched_port currently doing scheduling and then the code execurte
> rte_sched_port_free() for the unreference (reference by temporal pointer)
> rte_sched_port . This is the only way i found for applying dinamic
> configuration or changes to the qos framework.
> So, with this, what happens with the packets attached to the old
> rte_sched_port while is deleted? are those lost packets inside the
> rte_sched_port generates memory leaks?  how can i recover this packets _
> just dequeing from the port scheduler? Where the port scheduler  indicates
> empty packets in the queu state?
> 
> Is there a better way to achieve this kind of behaviour? i just need to
> update  the rte_sched_port configuration dinamically, and i want to change
> the current pipe configuration and sub port configuration also.
> 
> Regards .

If you need to do dynamic changes, I would recommend using an RCU type
algorithm where you exchange in new parameters and then cleanup/free
after a grace period.  See http://lttng.org/urcu

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