"
This series optimises the read path by replacing some usages of
std::vector by utils::small_vector. The motivation for this change was
an observation that memory allocation functions are pointed out by the
profiler as the ones where we spent most time and while they have a
large number of callers storage allocation for some vectors was close to
the top. The gains are not huge, since the problem is a lot of things
adding up and not a single slow thing, but we need to start with
something.
Unfortunately, the performance of boost::container::small_vector is
quite disappointing so a new implementation of a small_vector was
introduced.
perf_simple_query -c4 --duration 60, medians:
./perf_before ./perf_after diff
read 343086.80 360720.53 5.1%
Tests: unit(release, small_vector in debug)
"
* tag 'small_vector/v2.1' of https://github.com/pdziepak/scylla:
partition_slice: use small_vector for column_ids
mutation_fragment_merger: use small_vector
auth: use small_vector in resource
auth: avoid list-initialisation of vectors
idl: serialiser: add serialiser for utils::small_vector
idl: serialiser: deduplicate vector serialisers
utils: introduce small_vector
intrusive_set_external_comparator: make iterator nothrow move constructible
mutation_fragment_merger: value-initialise iterator
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