From bb2d2877c47fc770113f6fe336b93d52ab515862 Mon Sep 17 00:00:00 2001
From: Leonid Yuriev <leo@yuriev.ru>
Date: Sat, 9 Nov 2019 00:05:30 +0300
Subject: [PATCH] mdbx: add auto-readahead note/description.

Change-Id: Ie425416fd1afe9092b73acae4a7e3cdb5c3d8168
---
 mdbx.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/mdbx.h b/mdbx.h
index 41eeb6a9..ca388dfd 100644
--- a/mdbx.h
+++ b/mdbx.h
@@ -973,6 +973,12 @@ LIBMDBX_API const char *mdbx_dump_val(const MDBX_val *key, char *const buf,
  * may help random read performance when the DB is larger than RAM and system
  * RAM is full.
  *
+ * By default libmdbx dynamically enables/disables readahead depending on the
+ * actual database size and currently available memory. On the other hand, such
+ * automation has some limitation, i.e. could be performed only when DB size
+ * changing but can't tracks and reacts changing a free RAM availability, since
+ * it changes independently and asynchronously.
+ *
  * NOTE: The mdbx_is_readahead_reasonable() function allows to quickly find out
  *       whether to use readahead or not based on the size of the data and the
  *       amount of available memory.