Re: [dpdk-dev] Regarding mbuf allocation/free in secondary process

[Saravana Kumar <maheshmcc39@gmail.com>]

Thanks for your response..

Sara

On Wed, Feb 10, 2016 at 2:01 AM, Bruce Richardson <
bruce.richardson@intel.com> wrote:

> On Tue, Feb 09, 2016 at 11:43:19PM -0800, Saravana Kumar wrote:
> > Hi DPDK community,
> >
> >
> >
> > I'd like to have DPDK NIC IO operations in (primary) process and
> > execution logic in (secondary) processes.
> > Primary process pushes NIC Rx mbufs to Secondary process through S/W ring
> >
> > Seconary process allocates mbuf for Tx path and pushes down to Primary
> > process for NIC Tx
> >
> >
> > I have few doubts here:
> >
> > 1. If Secondary process dies because of SIGKILL then how can the mbufs
> > allocated in Secondary process can be freed.
> >    If it is normal signals like SIGINT/SIGTERM then we can be catch
> > those and free in those respective signal handlers
>
> If a process terminates abnormally then the buffers being used by that
> process
> may well be leaked. The solution you propose of catching signals will
> certainly
> help as you want to try and ensure that a process always frees all its
> buffers
> properly on termination.
>
> >
> > 2. Secondary process needs to poll on the S/W ring. This can consume
> 100% cpu.
> >    Is there a way to avoid polling in secondary process for Rx path
>
> Not using DPDK software rings, no. You'd have to use some kernel
> constructs such as
> fifo's/named pipes to do blocking reads on those. However, the overhead of
> using
> such structures can be severe making them unusable for many packet
> processing
> applications. An alternative might be to use some small sleep calls i.e.
> nanosleep
> between polls of the SW ring in cases where traffic rates are low. That
> will
> reduce your cpu usage.
>
> /Bruce
>
>