[ovs-dev] [v13 00/12] DPIF Framework + Optimizations

Cian Ferriter cian.ferriter at intel.com
Thu Jun 17 16:18:13 UTC 2021

v13 Summary:
- Squash DPCLS function rename commit into the first refactor commit.
- Add NEWS items in the commits where the features are added.
- Add documentation in the commits where the features are added.
- Squash commit which adds HWOL support to AVX512 DPIF into commit which
  adds the AVX512 DPIF.
- Add EMC and SMC batch insert functions for better handling of EMC and
  SMC in AVX512 DPIF.
- Document added commands in manpages as well as rST.

v12 Summary:
- Add a partial HWOL PMD statistic. This is added for both the scalar
  and AVX512 DPIFs.

v11 Summary:
- Improve the dp_netdev_impl_get_default() function so PMD threads created
  after running "dpif-set" command will use the DPIF implementation that was
- Fix small comment formatting issues.

v10 Summary:
- Removed AVX512 POC work for DPIF and MFEX which was added in v9
-- MFEX patches will be sent separately
- Rebase additions to NEWS entries
- Update copyright notices

v9 Summary:
- Added AVX512 POC work for DPIF and MFEX in single patch at end
-- Note that the AVX512 MFEX is for Ether()/IP()/UDP() traffic.
-- A significant performance boost is possible with these optimizations.

v8 Summary:
- Added NEWS entries for significant changes
- Added scalar optimizations for datapath TX
- Patchset is now ready for merge in my opinion.

v7 summary:
- OVS Conference included DPIF overview, youtube link:
--- https://youtu.be/5dWyPxiXEhg
- Rebased and tested on the DPDK 20.11 v4 patch
--- Link: https://patchwork.ozlabs.org/project/openvswitch/list/?series=220645
--- Tested this series for shared/static builds
--- Tested this series with/without -march=<native,skylake,nehalem>
- Minor code improvements in DPIF component (see commits for details)
- Improved CPU ISA checks, caching results
- Commit message improvements (.'s etc)
- Added performance data of patchset
--- Note that the benchmark below does not utilize the AVX512-vpopcntdq
--- optimizations, and performance is expected to improve when used.
--- Further optimizations are planned that continue.

Benchmark Details & Results

Intel® Xeon® Gold 6230 CPU @2.10GHz
OVS*-DPDK* Phy-Phy Performance 4x 25G Ports - Total 1 million flows
1C1T-4P, 64-byte frame size, performance in mpps:

Results Table:
DPIF  | Scalar | Scalar | AVX512 | AVX512 |
DPCLS | Scalar | AVX512 | Scalar | AVX512 |
mpps  |  6.955 |  7.530 |  7.530 |  7.962 |

By enabling both AVX512 DPIF and DPCLS, packet forwarding
is  7.962 / 6.955 = 1.1447x faster, aka 14% speedup.

v6 summary:
- Rebase to DPDK 20.11 enabling patch
--- This creates a dependency, expect CI build failures on the last
    patch in this series if it is not applied!
- Small improvements to DPIF layer
--- EMC/SMC enabling in AVX512 DPIF cleanups
- CPU ISA flags are cached, lowering overhead
- Wilcard Classifier DPCLS
--- Refactor and cleanups for function names
--- Enable more subtable specializations
--- Enable AVX512 vpopcount instruction

v5 summary:
- Dropped MFEX optimizations, re-targetting to a later release
--- This allows focus of community reviews & development on DPIF
--- Note OVS Conference talk still introduces both DPIF and MFEX topics
- DPIF improvements
--- Better EMC/SMC handling
--- HWOL is enabled in the avx512 DPIF
--- Documentation & NEWS items added
--- Various smaller improvements

v4 summary:
- Updated and improve DPIF component
--- SMC now implemented
--- EMC handling improved
--- Novel batching method using AVX512 implemented
--- see commits for details
- Updated Miniflow Extract component
--- Improved AVX512 code path performance
--- Implemented multiple TODO item's in v3
--- Add "disable" implementation to return to scalar miniflow only
--- More fixes planned for v5/future revisions:
---- Rename command to better reflect usage
---- Improve dynamicness of patterns
---- Add more demo protocols to show usage
- Future work
--- Documentation/NEWS items
--- Statistics for optimized MFEX
- Note that this patchset will be discussed/presented at OvsConf soon :)

v3 update summary:
(Cian Ferriter helping with rebases, review and code cleanups)
- Split out partially related changes (these will be sent separately)
--- netdev output action optimization
--- avx512 dpcls 16-block support optimization
- Squash commit which moves netdev struct flow into the refactor commit:
--- Squash dpif-netdev: move netdev flow struct to header
--- Into dpif-netdev: Refactor to multiple header files
- Implement Miniflow extract for AVX-512 DPIF
--- A generic method of matching patterns and packets is implemented,
    providing traffic-pattern specific miniflow-extract acceleration.
--- The patterns today are hard-coded, however in a future patchset it
    is intended to make these runtime configurable, allowing users to
    optimize the SIMD miniflow extract for active traffic types.
- Notes:
--- 32 bit builds will be fixed in next release by adding flexible
    miniflow extract optimization selection.
--- AVX-512 VBMI ISA is not yet supported in OVS due to requiring the
    DPDK 20.11 update for RTE_CPUFLAG_*. Once on a newer DPDK this will
    be added.

v2 updates:
- Includes DPIF command switching at runtime
- Includes AVX512 DPIF implementation
- Includes some partially related changes (can be split out of set?)
--- netdev output action optimization
--- avx512 dpcls 16-block support optimization

This patchset is a v7 for making the DPIF components of the
userspace datapath more flexible. It has been refactored to be
more modular to encourage code-reuse, and scalable in that ISA
optimized implementations can be added and selected at runtime.

The same approach as has been previously used for DPCLS is used
here, where a function pointer allows selection of an implementation
at runtime.

Datapath features such as EMC, SMC and HWOL are shared between
implementations, hence they are refactored into seperate header files.
The file splitting also improves maintainability, as dpif_netdev.c
has ~9000 LOC, and very hard to modify due to many structs defined
locally in the .c file, ruling out re-usability in other .c files.

Questions welcomed! Regards, -Harry

Cian Ferriter (2):
  dpif-netdev: Add a partial HWOL PMD statistic.
  dpif-netdev-unixctl.man: Document subtable-lookup-* CMDs

Harry van Haaren (10):
  dpif-netdev: Refactor to multiple header files.
  dpif-netdev: Split HWOL out to own header file.
  dpif-netdev: Add function pointer for netdev input.
  dpif-avx512: Add ISA implementation of dpif.
  dpif-netdev: Add command to switch dpif implementation.
  dpif-netdev: Add command to get dpif implementations.
  dpif-netdev/dpcls-avx512: Enable 16 block processing.
  dpif-netdev/dpcls: Specialize more subtable signatures.
  dpdk: Cache result of CPU ISA checks.
  dpcls-avx512: Enable avx512 vector popcount instruction.

 Documentation/topics/dpdk/bridge.rst   |  42 ++
 NEWS                                   |  12 +
 acinclude.m4                           |  15 +
 configure.ac                           |   1 +
 lib/automake.mk                        |  12 +-
 lib/dpdk.c                             |  29 +-
 lib/dpif-netdev-avx512.c               | 344 +++++++++++
 lib/dpif-netdev-lookup-autovalidator.c |   1 -
 lib/dpif-netdev-lookup-avx512-gather.c | 294 ++++++---
 lib/dpif-netdev-lookup-generic.c       |   7 +-
 lib/dpif-netdev-lookup.h               |   2 +-
 lib/dpif-netdev-perf.c                 |   3 +
 lib/dpif-netdev-perf.h                 |   1 +
 lib/dpif-netdev-private-dfc.c          | 110 ++++
 lib/dpif-netdev-private-dfc.h          | 201 +++++++
 lib/dpif-netdev-private-dpcls.h        | 127 ++++
 lib/dpif-netdev-private-dpif.c         | 111 ++++
 lib/dpif-netdev-private-dpif.h         |  85 +++
 lib/dpif-netdev-private-flow.h         | 162 +++++
 lib/dpif-netdev-private-hwol.h         |  63 ++
 lib/dpif-netdev-private-thread.h       | 215 +++++++
 lib/dpif-netdev-private.h              | 123 ++--
 lib/dpif-netdev-unixctl.man            |  17 +
 lib/dpif-netdev.c                      | 799 +++++++------------------
 tests/pmd.at                           |   6 +-
 25 files changed, 2038 insertions(+), 744 deletions(-)
 create mode 100644 lib/dpif-netdev-avx512.c
 create mode 100644 lib/dpif-netdev-private-dfc.c
 create mode 100644 lib/dpif-netdev-private-dfc.h
 create mode 100644 lib/dpif-netdev-private-dpcls.h
 create mode 100644 lib/dpif-netdev-private-dpif.c
 create mode 100644 lib/dpif-netdev-private-dpif.h
 create mode 100644 lib/dpif-netdev-private-flow.h
 create mode 100644 lib/dpif-netdev-private-hwol.h
 create mode 100644 lib/dpif-netdev-private-thread.h


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