From d905678a87326195c71ce6da16933e671b0d90eb Mon Sep 17 00:00:00 2001
From: Paul Emmerich <paul.emmerich@croit.io>
Date: Fri, 5 Jun 2020 13:54:15 +0200
Subject: [PATCH] mds: make threshold for MDS_TRIM configurable

Fixes: https://tracker.ceph.com/issues/45906
Signed-off-by: Paul Emmerich <paul.emmerich@croit.io>
---
 doc/cephfs/health-messages.rst | 4 ++--
 src/common/options.cc          | 6 ++++++
 src/mds/Beacon.cc              | 4 ++--
 3 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/doc/cephfs/health-messages.rst b/doc/cephfs/health-messages.rst
index 2e79c7bfa15b7..54e334111e50c 100644
--- a/doc/cephfs/health-messages.rst
+++ b/doc/cephfs/health-messages.rst
@@ -59,8 +59,8 @@ by the setting ``mds_log_max_segments``, and when the number of segments
 exceeds that setting the MDS starts writing back metadata so that it
 can remove (trim) the oldest segments.  If this writeback is happening
 too slowly, or a software bug is preventing trimming, then this health
-message may appear.  The threshold for this message to appear is for the
-number of segments to be double ``mds_log_max_segments``.
+message may appear.  The threshold for this message to appear is controlled by
+the config option ``mds_log_warn_factor``, the default is 2.0.
 
 Message: "Client *name* failing to respond to capability release"
 Code: MDS_HEALTH_CLIENT_LATE_RELEASE, MDS_HEALTH_CLIENT_LATE_RELEASE_MANY
diff --git a/src/common/options.cc b/src/common/options.cc
index 3245ce0ac4bec..55bd19bb65874 100644
--- a/src/common/options.cc
+++ b/src/common/options.cc
@@ -7952,6 +7952,12 @@ std::vector<Option> get_mds_options() {
     .set_default(128)
     .set_description("maximum number of segments which may be untrimmed"),
 
+    Option("mds_log_warn_factor", Option::TYPE_FLOAT, Option::LEVEL_ADVANCED)
+    .set_default(2.0)
+    .set_min(1.0)
+    .set_flag(Option::FLAG_RUNTIME)
+    .set_description("trigger MDS_HEALTH_TRIM warning when the mds log is longer than mds_log_max_segments * mds_log_warn_factor"),
+
     Option("mds_bal_export_pin", Option::TYPE_BOOL, Option::LEVEL_ADVANCED)
     .set_default(true)
     .set_description("allow setting directory export pins to particular ranks"),
diff --git a/src/mds/Beacon.cc b/src/mds/Beacon.cc
index c6da7cd242a59..8869d6e1e21de 100644
--- a/src/mds/Beacon.cc
+++ b/src/mds/Beacon.cc
@@ -304,9 +304,9 @@ void Beacon::notify_health(MDSRank const *mds)
   }
 
   // Detect MDS_HEALTH_TRIM condition
-  // Arbitrary factor of 2, indicates MDS is not trimming promptly
+  // Indicates MDS is not trimming promptly
   {
-    if (mds->mdlog->get_num_segments() > (size_t)(g_conf()->mds_log_max_segments * 2)) {
+    if (mds->mdlog->get_num_segments() > (size_t)(g_conf()->mds_log_max_segments * g_conf().get_val<double>("mds_log_warn_factor"))) {
       std::ostringstream oss;
       oss << "Behind on trimming (" << mds->mdlog->get_num_segments()
         << "/" << g_conf()->mds_log_max_segments << ")";
-- 
2.39.5