Re: [dpdk-dev] [PATCH 0/3] DPDK ethdev callback support

[Declan Doherty <declan.doherty@intel.com>]

On 12/02/15 19:57, John McNamara wrote:
> This patchset is for a small addition to the ethdev library, to
> add in support for callbacks at the RX and TX stages. This allows
> packet processing to be done on packets before they get returned
> to applications using rte_eth_rx_burst call.
>
> See the RFC cover letter for the use cases:
>
>      http://dpdk.org/ml/archives/dev/2014-December/010491.html
>
> For this version we spent some time investigating Stephen Hemminger's
> suggestion of using the userspace RCU (read-copy-update) library for
> SMP safety:
>
>     http://urcu.so/
>
> The default liburcu (which defaulted to liburcu-mb) requires the least
> interaction from the end user but showed a 25% drop in packet throughput
> in the callback sample app.
>
> The liburcu-qsbr (quiescent state) variant showed a 1% drop in packet
> throughput in the callback sample app. However it requires registered
> RCU threads in the program to periodically announce quiescent states.
> This makes it more difficult to implement for end user applications.
>
> For this release we will document that callbacks should be added/removed
> on stopped ports.
>
> Version 1 changes:
>      * Added callback removal functions.
>      * Minor fixes.
>
>
> Richardson, Bruce (3):
>    ethdev: rename callbacks field to intr_cbs
>    ethdev: Add in data rxtx callback support
>    examples: example showing use of callbacks.
>
>   app/test/virtual_pmd.c                 |    2 +-
>   examples/rxtx_callbacks/Makefile       |   57 ++++++++
>   examples/rxtx_callbacks/basicfwd.c     |  222 ++++++++++++++++++++++++++++++++
>   examples/rxtx_callbacks/basicfwd.h     |   46 +++++++
>   lib/librte_ether/rte_ethdev.c          |  177 ++++++++++++++++++++++++--
>   lib/librte_ether/rte_ethdev.h          |  175 +++++++++++++++++++++++++-
>   lib/librte_pmd_bond/rte_eth_bond_api.c |    2 +-
>   7 files changed, 667 insertions(+), 14 deletions(-)
>   create mode 100644 examples/rxtx_callbacks/Makefile
>   create mode 100644 examples/rxtx_callbacks/basicfwd.c
>   create mode 100644 examples/rxtx_callbacks/basicfwd.h
>

Looks good to me, I'll ack the next version which has addressed the ABI 
issues Neil raised. Also, it should probably be noted in the doxygen 
comments for the add/remove rxtx callbacks that as currently implemented 
the addition/removal of callbacks isn't thread safe

Declan