[ovs-dev] [PATCH v5 4/6] classifier: Retire partitions.
blp at nicira.com
Wed Aug 26 17:15:40 UTC 2015
On Fri, Aug 21, 2015 at 03:25:21PM -0700, Jarno Rajahalme wrote:
> Classifier partitions allowed skipping subtables when if was known
> from the flow's metadata field that the subtable cannot possibly
> match. This functionality was later implemented in a more general
> fashion by staged lookup, where the first stage also covers the
> metadata field, among the rest of the non-packet fields in the struct
> flow. While in theory skipping a subtable on the basis of the
> metadata field alone could produce more effective wildcards, on the
> basis of our testsuite coverage it does not seem to be the case, as
> removing the partitioning feature did not result in any test failures.
I don't understand this part of the rationale. Why would removing a
classifier optimization cause test failures?
> Removing the partitioning feature makes classifier lookups roughly 20%
> faster when a wildcard mask is not needed, and roughly 10% faster when
> a wildcard mask is needed, as tested with the test-classifier
> benchmark with one lookup thread.
> Found by profiling with 'perf'.
> Signed-off-by: Jarno Rajahalme <jrajahalme at nicira.com>
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