[SPARK-11710] Document new memory management model

Author: Andrew Or <andrew@databricks.com>

Closes #9676 from andrewor14/memory-management-docs.

1 files changed, 8 insertions, 5 deletions

diff --git a/docs/configuration.md b/docs/configuration.md
index d961f43acf..c496146e3e 100644
--- a/docs/configuration.md
+++ b/docs/configuration.md
@@ -722,17 +722,20 @@ Apart from these, the following properties are also available, and may be useful
     Fraction of the heap space used for execution and storage. The lower this is, the more
     frequently spills and cached data eviction occur. The purpose of this config is to set
     aside memory for internal metadata, user data structures, and imprecise size estimation
-    in the case of sparse, unusually large records.
+    in the case of sparse, unusually large records. Leaving this at the default value is
+    recommended. For more detail, see <a href="tuning.html#memory-management-overview">
+    this description</a>.
   </td>
 </tr>
 <tr>
   <td><code>spark.memory.storageFraction</code></td>
   <td>0.5</td>
   <td>
-    T​he size of the storage region within the space set aside by
-    <code>s​park.memory.fraction</code>. This region is not statically reserved, but dynamically
-    allocated as cache requests come in. ​Cached data may be evicted only if total storage exceeds
-    this region.
+    Amount of storage memory immune to eviction, expressed as a fraction of the size of the
+    region set aside by <code>s​park.memory.fraction</code>. The higher this is, the less
+    working memory may be available to execution and tasks may spill to disk more often.
+    Leaving this at the default value is recommended. For more detail, see
+    <a href="tuning.html#memory-management-overview">this description</a>.
   </td>
 </tr>
 <tr>