Switch to Cumulative instead of Total for summary

Use cumulative instead of total for summary reports and comparisons
and clarify that min/median/max are across primary shards.

Relates: elastic/elasticsearch#35594 (comment)

docs/metrics.rst

@@ -143,15 +143,15 @@ Rally stores the following metrics:
 * ``segments_terms_memory_in_bytes``: Number of bytes used for terms as reported by the indices stats API.
 * ``segments_norms_memory_in_bytes``: Number of bytes used for norms as reported by the indices stats API.
 * ``segments_points_memory_in_bytes``: Number of bytes used for points as reported by the indices stats API.
-* ``merges_total_time``: Total runtime of merges of primary shards, as reported by the indices stats API. Note that this is not Wall clock time (i.e. if M merge threads ran for N minutes, we will report M * N minutes, not N minutes). These metrics records also have a ``per-shard`` property that contains the times per primary shard in an array.
-* ``merges_total_count``: Total number of merges of primary shards, as reported by indices stats API under ``_all/primaries``.
-* ``merges_total_throttled_time``: Total time within merges have been throttled as reported by the indices stats API. Note that this is not Wall clock time.  These metrics records also have a ``per-shard`` property that contains the times per primary shard in an array.
-* ``indexing_total_time``: Total time used for indexing of primary shards, as reported by the indices stats API. Note that this is not Wall clock time.  These metrics records also have a ``per-shard`` property that contains the times per primary shard in an array.
-* ``indexing_throttle_time``: Total time that indexing has been throttled, as reported by the indices stats API. Note that this is not Wall clock time.  These metrics records also have a ``per-shard`` property that contains the times per primary shard in an array.
-* ``refresh_total_time``: Total time used for index refresh of primary shards, as reported by the indices stats API. Note that this is not Wall clock time.  These metrics records also have a ``per-shard`` property that contains the times per primary shard in an array.
-* ``refresh_total_count``: Total number of refreshes of primary shards, as reported by indices stats API under ``_all/primaries``.
-* ``flush_total_time``: Total time used for index flush of primary shards, as reported by the indices stats API. Note that this is not Wall clock time.  These metrics records also have a ``per-shard`` property that contains the times per primary shard in an array.
-* ``flush_total_count``: Total number of flushes of primary shards, as reported by indices stats API under ``_all/primaries``.
+* ``merges_total_time``: Cumulative runtime of merges of primary shards, as reported by the indices stats API. Note that this is not Wall clock time (i.e. if M merge threads ran for N minutes, we will report M * N minutes, not N minutes). These metrics records also have a ``per-shard`` property that contains the times across primary shards in an array.
+* ``merges_total_count``: Cumulative number of merges of primary shards, as reported by indices stats API under ``_all/primaries``.
+* ``merges_total_throttled_time``: Cumulative time within merges have been throttled as reported by the indices stats API. Note that this is not Wall clock time.  These metrics records also have a ``per-shard`` property that contains the times across primary shards in an array.
+* ``indexing_total_time``: Cumulative time used for indexing of primary shards, as reported by the indices stats API. Note that this is not Wall clock time.  These metrics records also have a ``per-shard`` property that contains the times across primary shards in an array.
+* ``indexing_throttle_time``: Cumulative time that indexing has been throttled, as reported by the indices stats API. Note that this is not Wall clock time.  These metrics records also have a ``per-shard`` property that contains the times across primary shards in an array.
+* ``refresh_total_time``: Cumulative time used for index refresh of primary shards, as reported by the indices stats API. Note that this is not Wall clock time.  These metrics records also have a ``per-shard`` property that contains the times across primary shards in an array.
+* ``refresh_total_count``: Cumulative number of refreshes of primary shards, as reported by indices stats API under ``_all/primaries``.
+* ``flush_total_time``: Cumulative time used for index flush of primary shards, as reported by the indices stats API. Note that this is not Wall clock time.  These metrics records also have a ``per-shard`` property that contains the times across primary shards in an array.
+* ``flush_total_count``: Cumulative number of flushes of primary shards, as reported by indices stats API under ``_all/primaries``.
 * ``final_index_size_bytes``: Final resulting index size on the file system after all nodes have been shutdown at the end of the benchmark. It includes all files in the nodes' data directories (actual index files and translog).
 * ``store_size_in_bytes``: The size in bytes of the index (excluding the translog), as reported by the indices stats API.
 * ``translog_size_in_bytes``: The size in bytes of the translog, as reported by the indices stats API.