[dpdk-dev] [PATCH RFCv3 00/19] ring cleanup and generalization

[Bruce Richardson]

This patchset make a set of, sometimes non-backward compatible, cleanup
changes to the rte_ring code in order to improve it. The resulting code is
shorter*, since the existing functions are restructured to reduce code
duplication, as well as being more consistent in behaviour. The specific
changes made are explained in each patch which makes that change.

Key incompatibilities:
* The biggest, and probably most controversial change is that to the
  enqueue and dequeue APIs. The enqueue/deq burst and bulk functions have
  their function prototypes changed so that they all return an additional
  parameter, indicating the size of next call which is guaranteed to
  succeed. In case on enq, this is the number of available slots on the
  ring, and in case of deq, it is the number of objects which can be
  pulled. As well as this, the return value from the bulk functions have
  been changed to make them compatible with the burst functions. In all
  cases, the functions to enq/deq a set of objs now return the number of
  objects processed, 0 or N, in the case of bulk functions, 0, N or any
  value in between in the case of the burst ones. [Due to the extra
  parameter, the compiler will flag all instances of the function to
  allow the user to also change the return value logic at the same time]
* The parameters to the single object enq/deq functions have not been 
  changed. Because of that, the return value is also unmodified - as the
  compiler cannot automatically flag this to the user.

Potential further cleanups:
* To a certain extent the rte_ring structure has gone from being a whole
  ring structure, including a "ring" element itself, to just being a
  header which can be reused, along with the head/tail update functions
  to create new rings. For now, the enqueue code works by assuming
  that the ring data goes immediately after the header, but that can
  be changed to allow specialised ring implementations to put additional
  metadata of their own after the ring header. I didn't see this as being
  needed right now, but it may be worth considering for a V1 patchset.
* There are 9 enqueue functions and 9 dequeue functions in rte_ring.h. I
  suspect not all of those are used, so personally I would consider
  dropping the functions to enqueue/dequeue a single value using single
  or multi semantics, i.e. drop 
    rte_ring_sp_enqueue
    rte_ring_mp_enqueue
    rte_ring_sc_dequeue
    rte_ring_mc_dequeue
  That would still leave a single enqueue and dequeue function for working
  with a single object at a time.
* It should be possible to merge the head update code for enqueue and
  dequeue into a single function. The key difference between the two is
  the calculation of how far the index can be moved. I felt that the
  functions for moving the head index are sufficiently complicated with
  many parameters to them already, that trying to merge in more code would
  impede readability. However, if so desired this change can be made at a
  later stage without affecting ABI or API.

PERFORMANCE:
I've run performance autotests on a couple of (Intel) platforms. Looking
particularly at the core-2-core results, which I expect are the main ones
of interest, the performance after this patchset is a few cycles per packet
faster in my testing. I'm hoping it should be at least neutral perf-wise.

REQUEST FOR FEEDBACK:
* Are all of these changes worth making?
* Should they be made in existing ring code, or do we look to provide a 
  new fifo library to completely replace the ring one?
* How does the implementation of new ring types using this code compare vs
  that of the previous RFCs?

[*] LOC original rte_ring.h: 462. After patchset: 363. [Numbers generated
using David A. Wheeler's 'SLOCCount'.]

Bruce Richardson (19):
  app/pdump: fix duplicate macro definition
  ring: remove split cacheline build setting
  ring: create common structure for prod and cons metadata
  ring: add a function to return the ring size
  crypto/null: use ring size function
  ring: eliminate duplication of size and mask fields
  ring: remove debug setting
  ring: remove the yield when waiting for tail update
  ring: remove watermark support
  ring: make bulk and burst fn return vals consistent
  ring: allow enq fns to return free space value
  examples/quota_watermark: use ring space for watermarks
  ring: allow dequeue fns to return remaining entry count
  ring: reduce scope of local variables
  ring: separate out head index manipulation for enq/deq
  ring: create common function for updating tail idx
  ring: allow macros to work with any type of object
  ring: add object size parameter to memory size calculation
  ring: add event ring implementation

 app/pdump/main.c                                   |   3 +-
 app/test-pipeline/pipeline_hash.c                  |   5 +-
 app/test-pipeline/runtime.c                        |  19 +-
 app/test/Makefile                                  |   1 +
 app/test/commands.c                                |  52 --
 app/test/test_event_ring.c                         |  85 +++
 app/test/test_link_bonding_mode4.c                 |   6 +-
 app/test/test_pmd_ring_perf.c                      |  12 +-
 app/test/test_ring.c                               | 704 ++-----------------
 app/test/test_ring_perf.c                          |  36 +-
 app/test/test_table_acl.c                          |   2 +-
 app/test/test_table_pipeline.c                     |   2 +-
 app/test/test_table_ports.c                        |  12 +-
 app/test/virtual_pmd.c                             |   8 +-
 config/common_base                                 |   3 -
 doc/guides/prog_guide/env_abstraction_layer.rst    |   5 -
 doc/guides/prog_guide/ring_lib.rst                 |   7 -
 doc/guides/sample_app_ug/server_node_efd.rst       |   2 +-
 drivers/crypto/null/null_crypto_pmd.c              |   2 +-
 drivers/crypto/null/null_crypto_pmd_ops.c          |   2 +-
 drivers/net/bonding/rte_eth_bond_pmd.c             |   3 +-
 drivers/net/ring/rte_eth_ring.c                    |   4 +-
 examples/distributor/main.c                        |   5 +-
 examples/load_balancer/runtime.c                   |  34 +-
 .../client_server_mp/mp_client/client.c            |   9 +-
 .../client_server_mp/mp_server/main.c              |   2 +-
 examples/packet_ordering/main.c                    |  13 +-
 examples/qos_sched/app_thread.c                    |  14 +-
 examples/quota_watermark/qw/init.c                 |   5 +-
 examples/quota_watermark/qw/main.c                 |  15 +-
 examples/quota_watermark/qw/main.h                 |   1 +
 examples/quota_watermark/qwctl/commands.c          |   2 +-
 examples/quota_watermark/qwctl/qwctl.c             |   2 +
 examples/quota_watermark/qwctl/qwctl.h             |   1 +
 examples/server_node_efd/node/node.c               |   2 +-
 examples/server_node_efd/server/main.c             |   2 +-
 lib/librte_hash/rte_cuckoo_hash.c                  |   5 +-
 lib/librte_mempool/rte_mempool_ring.c              |  12 +-
 lib/librte_pdump/rte_pdump.c                       |   2 +-
 lib/librte_port/rte_port_frag.c                    |   3 +-
 lib/librte_port/rte_port_ras.c                     |   2 +-
 lib/librte_port/rte_port_ring.c                    |  34 +-
 lib/librte_ring/Makefile                           |   2 +
 lib/librte_ring/rte_event_ring.c                   | 220 ++++++
 lib/librte_ring/rte_event_ring.h                   | 507 ++++++++++++++
 lib/librte_ring/rte_ring.c                         |  82 +--
 lib/librte_ring/rte_ring.h                         | 762 ++++++++-------------
 47 files changed, 1340 insertions(+), 1373 deletions(-)
 create mode 100644 app/test/test_event_ring.c
 create mode 100644 lib/librte_ring/rte_event_ring.c
 create mode 100644 lib/librte_ring/rte_event_ring.h

-- 
2.9.3