Merge PR #60381 into main

* refs/pull/60381/head:
	doc: remove refrences to `mds_log_major_segment_event_ratio`
	mds: start a new major segment after reaching minor segment threshold
	mds: make parts of mdlog reusable to be used by beacon

Reviewed-by: Anthony D Atri <anthony.datri@gmail.com>
Reviewed-by: Patrick Donnelly <pdonnell@ibm.com>

doc/cephfs/mds-journaling.rst

@@ -141,14 +141,12 @@ The targetted size of a log segment in terms of number of events is controlled b
 
 .. confval:: mds_log_events_per_segment
 
-The frequency of major segments (noted by the journaling of the latest ``ESubtreeMap``) is controlled by:
+The number of minor mds log segments since last major segment is controlled by:
 
-.. confval:: mds_log_major_segment_event_ratio
+.. confval:: mds_log_minor_segments_per_major_segment
 
-When ``mds_log_events_per_segment * mds_log_major_segment_event_ratio``
-non-``ESubtreeMap`` events are logged, the MDS will journal a new
-``ESubtreeMap``. This is necessary to allow the journal to shrink in size
-during the trimming of expired segments.
+This controls how often the MDS trims expired log segments (higher the value, less
+often the MDS updates the journal expiry position for trimming).
 
 The target maximum number of segments is controlled by:
 

src/common/options/mds.yaml.in

@@ -586,16 +586,6 @@ options:
   min: 1
   services:
   - mds
-- name: mds_log_major_segment_event_ratio
-  type: uint
-  level: advanced
-  desc: multiple of mds_log_events_per_segment between major segments
-  default: 12
-  services:
-  - mds
-  min: 1
-  see_also:
-  - mds_log_events_per_segment
 # segment size for mds log, default to default file_layout_t
 - name: mds_log_segment_size
   type: size
@@ -1741,3 +1731,12 @@ options:
   - mds
   flags:
   - runtime
+- name: mds_log_minor_segments_per_major_segment
+  type: uint
+  level: advanced
+  desc: number of minor segments per major segment.
+  long_desc: The number of minor mds log segments since last major segment after which a major segment is started/logged.
+  default: 16
+  services:
+  - mds
+  min: 8

src/mds/Beacon.cc

@@ -321,16 +321,15 @@ void Beacon::notify_health(MDSRank const *mds)
   // Detect MDS_HEALTH_TRIM condition
   // Indicates MDS is not trimming promptly
   {
-    const auto log_max_segments = mds->mdlog->get_max_segments();
-    const auto log_warn_factor = g_conf().get_val<double>("mds_log_warn_factor");
-    if (mds->mdlog->get_num_segments() > (size_t)(log_max_segments * log_warn_factor)) {
+    if (mds->mdlog->is_trim_slow()) {
+      auto num_segments = mds->mdlog->get_num_segments();
+      auto max_segments = mds->mdlog->get_max_segments();
       CachedStackStringStream css;
-      *css << "Behind on trimming (" << mds->mdlog->get_num_segments()
-        << "/" << log_max_segments << ")";
+      *css << "Behind on trimming (" << num_segments << "/" << max_segments << ")";
 
       MDSHealthMetric m(MDS_HEALTH_TRIM, HEALTH_WARN, css->strv());
-      m.metadata["num_segments"] = stringify(mds->mdlog->get_num_segments());
-      m.metadata["max_segments"] = stringify(log_max_segments);
+      m.metadata["num_segments"] = stringify(num_segments);
+      m.metadata["max_segments"] = stringify(max_segments);
       health.metrics.push_back(m);
     }
   }

src/mds/MDLog.cc

@@ -53,11 +53,12 @@ MDLog::MDLog(MDSRank* m)
   event_large_threshold = g_conf().get_val<uint64_t>("mds_log_event_large_threshold");
   events_per_segment = g_conf().get_val<uint64_t>("mds_log_events_per_segment");
   pause = g_conf().get_val<bool>("mds_log_pause");
-  major_segment_event_ratio = g_conf().get_val<uint64_t>("mds_log_major_segment_event_ratio");
   max_segments = g_conf().get_val<uint64_t>("mds_log_max_segments");
   max_events = g_conf().get_val<int64_t>("mds_log_max_events");
   skip_corrupt_events = g_conf().get_val<bool>("mds_log_skip_corrupt_events");
   skip_unbounded_events = g_conf().get_val<bool>("mds_log_skip_unbounded_events");
+  log_warn_factor = g_conf().get_val<double>("mds_log_warn_factor");
+  minor_segments_per_major_segment = g_conf().get_val<uint64_t>("mds_log_minor_segments_per_major_segment");
   upkeep_thread = std::thread(&MDLog::log_trim_upkeep, this);
 }
 
@@ -357,14 +358,15 @@ void MDLog::_submit_entry(LogEvent *le, MDSLogContextBase* c)
   ceph_assert(!mds_is_shutting_down);
 
   event_seq++;
-  events_since_last_major_segment++;
 
   if (auto sb = dynamic_cast<SegmentBoundary*>(le); sb) {
     auto ls = _start_new_segment(sb);
     if (sb->is_major_segment_boundary()) {
       major_segments.insert(ls->seq);
       logger->set(l_mdl_segmjr, major_segments.size());
-      events_since_last_major_segment = 0;
+      minor_segments_since_last_major_segment = 0;
+    } else {
+      ++minor_segments_since_last_major_segment;
     }
   }
 
@@ -403,7 +405,7 @@ void MDLog::_segment_upkeep()
   uint64_t period = journaler->get_layout_period();
   auto ls = get_current_segment();
   // start a new segment?
-  if (events_since_last_major_segment > events_per_segment*major_segment_event_ratio) {
+  if (minor_segments_since_last_major_segment > minor_segments_per_major_segment) {
     dout(10) << __func__ << ": starting new major segment, current " << *ls << dendl;
     auto sle = mds->mdcache->create_subtree_map();
     _submit_entry(sle, NULL);
@@ -656,6 +658,10 @@ void MDLog::try_to_commit_open_file_table(uint64_t last_seq)
   }
 }
 
+bool MDLog::is_trim_slow() const {
+  return (segments.size() > (size_t)(max_segments * log_warn_factor));
+}
+
 void MDLog::log_trim_upkeep(void) {
   dout(10) << dendl;
 
@@ -1474,7 +1480,6 @@ void MDLog::_replay_thread()
     }
     le->set_start_off(pos);
 
-    events_since_last_major_segment++;
     if (auto sb = dynamic_cast<SegmentBoundary*>(le.get()); sb) {
       auto seq = sb->get_seq();
       if (seq > 0) {
@@ -1487,7 +1492,9 @@ void MDLog::_replay_thread()
       if (sb->is_major_segment_boundary()) {
         major_segments.insert(event_seq);
         logger->set(l_mdl_segmjr, major_segments.size());
-        events_since_last_major_segment = 0;
+	minor_segments_since_last_major_segment = 0;
+      } else {
+	++minor_segments_since_last_major_segment;
       }
     } else {
       event_seq++;
@@ -1618,9 +1625,6 @@ void MDLog::handle_conf_change(const std::set<std::string>& changed, const MDSMa
   if (changed.count("mds_log_events_per_segment")) {
     events_per_segment = g_conf().get_val<uint64_t>("mds_log_events_per_segment");
   }
-  if (changed.count("mds_log_major_segment_event_ratio")) {
-    major_segment_event_ratio = g_conf().get_val<uint64_t>("mds_log_major_segment_event_ratio");
-  }
   if (changed.count("mds_log_max_events")) {
     max_events = g_conf().get_val<int64_t>("mds_log_max_events");
   }
@@ -1642,4 +1646,10 @@ void MDLog::handle_conf_change(const std::set<std::string>& changed, const MDSMa
   if (changed.count("mds_log_trim_decay_rate")){
     log_trim_counter = DecayCounter(g_conf().get_val<double>("mds_log_trim_decay_rate"));
   }
+  if (changed.count("mds_log_warn_factor")) {
+    log_warn_factor = g_conf().get_val<double>("mds_log_warn_factor");
+  }
+  if (changed.count("mds_log_minor_segments_per_major_segment")) {
+    minor_segments_per_major_segment = g_conf().get_val<uint64_t>("mds_log_minor_segments_per_major_segment");
+  }
 }

src/mds/MDLog.h

@@ -173,6 +173,9 @@ public:
   // replay state
   std::map<inodeno_t, std::set<inodeno_t>> pending_exports;
 
+  // beacon needs me too
+  bool is_trim_slow() const;
+
 protected:
   struct PendingEvent {
     PendingEvent(LogEvent *e, Context* c, bool f=false) : le(e), fin(c), flush(f) {}
@@ -302,9 +305,9 @@ private:
   bool debug_subtrees;
   std::atomic_uint64_t event_large_threshold; // accessed by submit thread
   uint64_t events_per_segment;
-  uint64_t major_segment_event_ratio;
   int64_t max_events;
   uint64_t max_segments;
+  uint64_t minor_segments_per_major_segment;
   bool pause;
   bool skip_corrupt_events;
   bool skip_unbounded_events;
@@ -312,7 +315,8 @@ private:
   std::set<uint64_t> major_segments;
   std::set<LogSegment*> expired_segments;
   std::set<LogSegment*> expiring_segments;
-  uint64_t events_since_last_major_segment = 0;
+  uint64_t minor_segments_since_last_major_segment = 0;
+  double log_warn_factor;
 
   // log trimming decay counter
   DecayCounter log_trim_counter;