update cli parameter description (#1760)

Signed-off-by: Mauro Stettler <mauro.stettler@gmail.com>

cmd/mimir/config-descriptor.json

@@ -5307,7 +5307,7 @@
               "kind": "field",
               "name": "head_chunks_write_queue_size",
               "required": false,
-              "desc": "The size of the write queue used by the head chunks mapper. Lower values reduce memory utilisation at the cost of potentially higher ingest latency. Value of 0 switches chunks mapper to implementation without a queue.",
+              "desc": "The size of the write queue used by the head chunks mapper. Lower values reduce memory utilisation at the cost of potentially higher ingest latency. Value of 0 switches chunks mapper to implementation without a queue. This flag is only used if the new chunk disk mapper is enabled with -blocks-storage.tsdb.new-chunk-disk-mapper.",
               "fieldValue": null,
               "fieldDefaultValue": 0,
               "fieldFlag": "blocks-storage.tsdb.head-chunks-write-queue-size",

cmd/mimir/help-all.txt.tmpl

@@ -486,7 +486,7 @@ Usage of ./cmd/mimir/mimir:
   -blocks-storage.tsdb.head-chunks-write-buffer-size-bytes int
     	The write buffer size used by the head chunks mapper. Lower values reduce memory utilisation on clusters with a large number of tenants at the cost of increased disk I/O operations. (default 4194304)
   -blocks-storage.tsdb.head-chunks-write-queue-size int
-    	[experimental] The size of the write queue used by the head chunks mapper. Lower values reduce memory utilisation at the cost of potentially higher ingest latency. Value of 0 switches chunks mapper to implementation without a queue.
+    	[experimental] The size of the write queue used by the head chunks mapper. Lower values reduce memory utilisation at the cost of potentially higher ingest latency. Value of 0 switches chunks mapper to implementation without a queue. This flag is only used if the new chunk disk mapper is enabled with -blocks-storage.tsdb.new-chunk-disk-mapper.
   -blocks-storage.tsdb.head-compaction-concurrency int
     	Maximum number of tenants concurrently compacting TSDB head into a new block (default 5)
   -blocks-storage.tsdb.head-compaction-idle-timeout duration

docs/sources/operators-guide/configuring/reference-configuration-parameters/index.md

@@ -3438,7 +3438,8 @@ tsdb:
   # (experimental) The size of the write queue used by the head chunks mapper.
   # Lower values reduce memory utilisation at the cost of potentially higher
   # ingest latency. Value of 0 switches chunks mapper to implementation without
-  # a queue.
+  # a queue. This flag is only used if the new chunk disk mapper is enabled with
+  # -blocks-storage.tsdb.new-chunk-disk-mapper.
   # CLI flag: -blocks-storage.tsdb.head-chunks-write-queue-size
   [head_chunks_write_queue_size: <int> | default = 0]
 

pkg/storage/tsdb/config.go

@@ -198,7 +198,7 @@ func (cfg *TSDBConfig) RegisterFlags(f *flag.FlagSet) {
 	f.BoolVar(&cfg.FlushBlocksOnShutdown, "blocks-storage.tsdb.flush-blocks-on-shutdown", false, "True to flush blocks to storage on shutdown. If false, incomplete blocks will be reused after restart.")
 	f.DurationVar(&cfg.CloseIdleTSDBTimeout, "blocks-storage.tsdb.close-idle-tsdb-timeout", 13*time.Hour, "If TSDB has not received any data for this duration, and all blocks from TSDB have been shipped, TSDB is closed and deleted from local disk. If set to positive value, this value should be equal or higher than -querier.query-ingesters-within flag to make sure that TSDB is not closed prematurely, which could cause partial query results. 0 or negative value disables closing of idle TSDB.")
 	f.BoolVar(&cfg.MemorySnapshotOnShutdown, "blocks-storage.tsdb.memory-snapshot-on-shutdown", false, "True to enable snapshotting of in-memory TSDB data on disk when shutting down.")
-	f.IntVar(&cfg.HeadChunksWriteQueueSize, "blocks-storage.tsdb.head-chunks-write-queue-size", 0, "The size of the write queue used by the head chunks mapper. Lower values reduce memory utilisation at the cost of potentially higher ingest latency. Value of 0 switches chunks mapper to implementation without a queue.")
+	f.IntVar(&cfg.HeadChunksWriteQueueSize, "blocks-storage.tsdb.head-chunks-write-queue-size", 0, "The size of the write queue used by the head chunks mapper. Lower values reduce memory utilisation at the cost of potentially higher ingest latency. Value of 0 switches chunks mapper to implementation without a queue. This flag is only used if the new chunk disk mapper is enabled with -blocks-storage.tsdb.new-chunk-disk-mapper.")
 	f.BoolVar(&cfg.NewChunkDiskMapper, "blocks-storage.tsdb.new-chunk-disk-mapper", false, "Temporary flag to select whether to use the new (used in upstream Prometheus) or the old (legacy) chunk disk mapper.")
 	f.BoolVar(&cfg.IsolationEnabled, "blocks-storage.tsdb.isolation-enabled", false, "[Deprecated] Enables TSDB isolation feature. Disabling may improve performance.")
 }