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| author | Harry van Haaren <harry.van.haaren@intel.com> | 2021-07-09 15:58:21 +0000 |
|---|---|---|
| committer | Ian Stokes <ian.stokes@intel.com> | 2021-07-09 17:14:14 +0100 |
| commit | 47a2a8f4138e64fb6644e62299b6a8a660ab4029 (patch) | |
| tree | a4e60264569fb0bef9669c24c2da1af48b1a4e35 /NEWS | |
| parent | d76a719a7aa0e040e943dfbc75e482fbb6350475 (diff) | |
| download | openvswitch-47a2a8f4138e64fb6644e62299b6a8a660ab4029.tar.gz | |
dpif-netdev/dpcls-avx512: Enable 16 block processing.
This commit implements larger subtable searches in avx512. A limitation
of the previous implementation was that up to 8 blocks of miniflow
data could be matched on (so a subtable with 8 blocks was handled
in avx, but 9 blocks or more would fall back to scalar/generic).
This limitation is removed in this patch, where up to 16 blocks
of subtable can be matched on.
From an implementation perspective, the key to enabling 16 blocks
over 8 blocks was to do bitmask calculation up front, and then use
the pre-calculated bitmasks for 2x passes of the "blocks gather"
routine. The bitmasks need to be shifted for k-mask usage in the
upper (8-15) block range, but it is relatively trivial. This also
helps in case expanding to 24 blocks is desired in future.
The implementation of the 2nd iteration to handle > 8 blocks is
behind a conditional branch which checks the total number of bits.
This helps the specialized versions of the function that have a
miniflow fingerprint of less-than-or-equal 8 blocks, as the code
can be statically stripped out of those functions. Specialized
functions that do require more than 8 blocks will have the branch
removed and unconditionally execute the 2nd blocks gather routine.
Lastly, the _any() flavour will have the conditional branch, and
the branch predictor may mispredict a bit, but per burst will
likely get most packets correct (particularly towards the middle
and end of a burst).
The code has been run with unit tests under autovalidation and
passes all cases, and unit test coverage has been checked to
ensure the 16 block code paths are executing.
Signed-off-by: Harry van Haaren <harry.van.haaren@intel.com>
Acked-by: Flavio Leitner <fbl@sysclose.org>
Signed-off-by: Ian Stokes <ian.stokes@intel.com>
Diffstat (limited to 'NEWS')
| -rw-r--r-- | NEWS | 1 |
1 files changed, 1 insertions, 0 deletions
@@ -26,6 +26,7 @@ Post-v2.15.0 * Add commands to get and set the dpif implementations. * Add a partial HWOL PMD statistic counting hits similar to existing EMC/SMC/DPCLS stats. + * Enable AVX512 optimized DPCLS to search subtables with larger miniflows. - ovs-ctl: * New option '--no-record-hostname' to disable hostname configuration in ovsdb on startup. |