From: Jan Fajerski <jfajerski@suse.com>
Date: Tue, 15 Dec 2020 12:34:31 +0000 (+0100)
Subject: doc: add explanatory note about cache trim rate setting
X-Git-Tag: v16.1.0~128^2
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=759155e9425b34864a9d6965fe09d086e7dadce4;p=ceph.git

doc: add explanatory note about cache trim rate setting

Fixes: https://tracker.ceph.com/issues/48585

Signed-off-by: Jan Fajerski <jfajerski@suse.com>
---

diff --git a/doc/cephfs/cache-configuration.rst b/doc/cephfs/cache-configuration.rst
index 94c970ee3960..e97432f4f884 100644
--- a/doc/cephfs/cache-configuration.rst
+++ b/doc/cephfs/cache-configuration.rst
@@ -77,6 +77,11 @@ life for the counter. If the MDS is continually removing items from its cache,
 it will reach a steady state of ``-ln(0.5)/rate*threshold`` items removed per
 second.
 
+.. note:: Increasing the value of the confguration setting
+          ``mds_cache_trim_decay_rate`` leads to the MDS spending less time
+          trimming the cache. To increase the cache trimming rate, set a lower
+          value.
+
 The defaults are conservative and may need to be changed for production MDS with
 large cache sizes.