Update docs and CHANGELOG for batched background cache

Signed-off-by: Bryan Boreham <[email protected]>

Author: bboreham

CHANGELOG.md

@@ -57,6 +57,7 @@
 * [ENHANCEMENT] Cassandra Storage: User no longer need `CREATE` privilege on `<all keyspaces>` if given keyspace exists. #2032
 * [ENHANCEMENT] Cassandra Storage: added `password_file` configuration options to enable reading Cassandra password from file. #2096
 * [ENHANCEMENT] Experimental Memberlist KV: expose `-memberlist.gossip-to-dead-nodes-time` and `-memberlist.dead-node-reclaim-time` options to control how memberlist library handles dead nodes and name reuse. #2131
+* [ENHANCEMENT] Background cache writes are batched to improve parallelism and observability. #2135
 * [BUGFIX] Alertmanager: fixed panic upon applying a new config, caused by duplicate metrics registration in the `NewPipelineBuilder` function. #211
 * [BUGFIX] Experimental TSDB: fixed `/all_user_stats` and `/api/prom/user_stats` endpoints when using the experimental TSDB blocks storage. #2042
 * [BUGFIX] Experimental TSDB: fixed ruler to correctly work with the experimental TSDB blocks storage. #2101

docs/configuration/config-file-reference.md

@@ -629,7 +629,7 @@ results_cache:
       # CLI flag: -frontend.memcache.write-back-goroutines
       [writeback_goroutines: <int> | default = 10]
 
-      # How many chunks to buffer for background write back.
+      # How many key batches to buffer for background write-back.
       # CLI flag: -frontend.memcache.write-back-buffer
       [writeback_buffer: <int> | default = 10000]
 
@@ -1501,8 +1501,8 @@ index_queries_cache_config:
     # CLI flag: -store.index-cache-read.memcache.write-back-goroutines
     [writeback_goroutines: <int> | default = 10]
 
-    # Cache config for index entry reading. How many chunks to buffer for
-    # background write back.
+    # Cache config for index entry reading. How many key batches to buffer for
+    # background write-back.
     # CLI flag: -store.index-cache-read.memcache.write-back-buffer
     [writeback_buffer: <int> | default = 10000]
 
@@ -1546,8 +1546,8 @@ chunk_cache_config:
     # CLI flag: -memcache.write-back-goroutines
     [writeback_goroutines: <int> | default = 10]
 
-    # Cache config for chunks. How many chunks to buffer for background write
-    # back.
+    # Cache config for chunks. How many key batches to buffer for background
+    # write-back.
     # CLI flag: -memcache.write-back-buffer
     [writeback_buffer: <int> | default = 10000]
 
@@ -1581,8 +1581,8 @@ write_dedupe_cache_config:
     # CLI flag: -store.index-cache-write.memcache.write-back-goroutines
     [writeback_goroutines: <int> | default = 10]
 
-    # Cache config for index entry writing. How many chunks to buffer for
-    # background write back.
+    # Cache config for index entry writing. How many key batches to buffer for
+    # background write-back.
     # CLI flag: -store.index-cache-write.memcache.write-back-buffer
     [writeback_buffer: <int> | default = 10000]