Set up scheduling groups for streaming, compaction, memtable flush, query,
and commitlog.
The background writer scheduling group is retired; it is split into
the memtable flush and compaction groups.
Comments from Glauber:
This patch is based in a patch from Avi with the same subject, but the
differences are signficant enough so that I reset authorship. In
particular:
1) A bug/regression is fixed with the boundary calculations for the
memtable controller sampling function.
2) A leftover is removed, where after flushing a memtable we would
go back to the main group before going to the cache group again
3) As per Tomek's suggestion, now the submission of compactions
themselves are run in the compaction scheduling group. Having that
working is what changes this patch the most: we now store the
scheduling group in the compaction manager and let the compaction
manager itself enforce the scheduling group.
Signed-off-by: Glauber Costa <glauber@scylladb.com>
956af9f099