[dpdk-dev] [PATCH v6 0/3] DPDK ethdev callback support

[John McNamara <john.mcnamara@intel.com>]

This patchset is for a small optional addition to the ethdev library,
to add 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 adding and removing callbacks
is not thread safe.

Note: Sample application documentation to follow in a patch update.

Version 6 changes:
    * RX/TX callback functions are no longer #ifdefed out if callback
      option is off. Instead they return ENOTSUP.
    * Simplified callbacks #ifdefs in rte_ethdev.

Version 5 changes:
    * Turned the callback feature on by default.
    * Simplified #define name.

Version 4 changes:
    * Made the callback feature a compile time option.

Version 3 changes:
    * Removed unnecessary header file from example folder
      (which included baremetal reference).
    * Renamed the interrupt, RX and TX callbacks to make their function
      clearer (using the names suggested in the mailing list comments).
    * Squashed ABI version update into the commit it relates to.
    * Fixed various checkpatch warnings.

Version 2 changes:
    * Added ABI versioning.
    * Doxygen clarifications.

Version 1 changes:
    * Added callback removal functions.
    * Minor fixes.


Richardson, Bruce (3):
  ethdev: rename callbacks field to link_intr_cbs
  ethdev: add optional rxtx callback support
  examples: example showing use of callbacks.

 MAINTAINERS                            |    4 +
 app/test/virtual_pmd.c                 |    2 +-
 config/common_bsdapp                   |    1 +
 config/common_linuxapp                 |    1 +
 examples/Makefile                      |    1 +
 examples/rxtx_callbacks/Makefile       |   57 ++++++++
 examples/rxtx_callbacks/main.c         |  228 ++++++++++++++++++++++++++++++++
 lib/librte_ether/rte_ethdev.c          |  216 ++++++++++++++++++++++++++++--
 lib/librte_ether/rte_ethdev.h          |  203 ++++++++++++++++++++++++++++-
 lib/librte_ether/rte_ether_version.map |    4 +
 lib/librte_pmd_bond/rte_eth_bond_api.c |    2 +-
 lib/librte_pmd_ring/rte_eth_ring.c     |    2 +-
 12 files changed, 706 insertions(+), 15 deletions(-)
 create mode 100644 examples/rxtx_callbacks/Makefile
 create mode 100644 examples/rxtx_callbacks/main.c

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1.7.4.1