Merge PR #32667 into master

* refs/pull/32667/head:
	mds: track high water mark for purges
	qa: use correct variable for exception debug
	mds: mark purge queue protected members private

Reviewed-by: Patrick Donnelly <pdonnell@redhat.com>

qa/tasks/cephfs/test_strays.py

@@ -194,11 +194,10 @@ class TestStrays(CephFSTestCase):
             num_strays = mdc_stats['num_strays']
             num_strays_purging = pq_stats['pq_executing']
             num_purge_ops = pq_stats['pq_executing_ops']
+            files_high_water = pq_stats['pq_executing_high_water']
+            ops_high_water = pq_stats['pq_executing_ops_high_water']
 
-            self.data_log.append([datetime.datetime.now(), num_strays, num_strays_purging, num_purge_ops])
-
-            files_high_water = max(files_high_water, num_strays_purging)
-            ops_high_water = max(ops_high_water, num_purge_ops)
+            self.data_log.append([datetime.datetime.now(), num_strays, num_strays_purging, num_purge_ops, files_high_water, ops_high_water])
 
             total_strays_created = mdc_stats['strays_created']
             total_strays_purged = pq_stats['pq_executed']
@@ -242,11 +241,18 @@ class TestStrays(CephFSTestCase):
                 raise RuntimeError("Ops in flight high water is unexpectedly low ({0} / {1})".format(
                     ops_high_water, mds_max_purge_ops
                 ))
+            # The MDS may go over mds_max_purge_ops for some items, like a
+            # heavily fragmented directory.  The throttle does not kick in
+            # until *after* we reach or exceed the limit.  This is expected
+            # because we don't want to starve the PQ or never purge a
+            # particularly large file/directory.
+            self.assertLessEqual(ops_high_water, mds_max_purge_ops+64)
         elif throttle_type == self.FILES_THROTTLE:
             if files_high_water < mds_max_purge_files / 2:
                 raise RuntimeError("Files in flight high water is unexpectedly low ({0} / {1})".format(
-                    ops_high_water, mds_max_purge_files
+                    files_high_water, mds_max_purge_files
                 ))
+            self.assertLessEqual(files_high_water, mds_max_purge_files)
 
         # Sanity check all MDC stray stats
         stats = self.fs.mds_asok(['perf', 'dump'])

src/mds/PurgeQueue.cc

@@ -114,7 +114,9 @@ void PurgeQueue::create_logger()
 
   pcb.set_prio_default(PerfCountersBuilder::PRIO_USEFUL);
   pcb.add_u64(l_pq_executing_ops, "pq_executing_ops", "Purge queue ops in flight");
+  pcb.add_u64(l_pq_executing_ops_high_water, "pq_executing_ops_high_water", "Maximum number of executing file purge ops");
   pcb.add_u64(l_pq_executing, "pq_executing", "Purge queue tasks in flight");
+  pcb.add_u64(l_pq_executing_high_water, "pq_executing_high_water", "Maximum number of executing file purges");
   pcb.add_u64(l_pq_item_in_journal, "pq_item_in_journal", "Purge item left in journal");
 
   logger.reset(pcb.create_perf_counters());
@@ -475,9 +477,13 @@ void PurgeQueue::_execute_item(
 
   in_flight[expire_to] = item;
   logger->set(l_pq_executing, in_flight.size());
+  files_high_water = std::max(files_high_water, in_flight.size());
+  logger->set(l_pq_executing_high_water, files_high_water);
   auto ops = _calculate_ops(item);
   ops_in_flight += ops;
   logger->set(l_pq_executing_ops, ops_in_flight);
+  ops_high_water = std::max(ops_high_water, ops_in_flight);
+  logger->set(l_pq_executing_ops_high_water, ops_high_water);
 
   SnapContext nullsnapc;
 
@@ -545,8 +551,12 @@ void PurgeQueue::_execute_item(
             "dropping it" << dendl;
     ops_in_flight -= ops;
     logger->set(l_pq_executing_ops, ops_in_flight);
+    ops_high_water = std::max(ops_high_water, ops_in_flight);
+    logger->set(l_pq_executing_ops_high_water, ops_high_water);
     in_flight.erase(expire_to);
     logger->set(l_pq_executing, in_flight.size());
+    files_high_water = std::max(files_high_water, in_flight.size());
+    logger->set(l_pq_executing_high_water, files_high_water);
     return;
   }
   ceph_assert(gather.has_subs());
@@ -610,11 +620,15 @@ void PurgeQueue::_execute_item_complete(
 
   ops_in_flight -= _calculate_ops(iter->second);
   logger->set(l_pq_executing_ops, ops_in_flight);
+  ops_high_water = std::max(ops_high_water, ops_in_flight);
+  logger->set(l_pq_executing_ops_high_water, ops_high_water);
 
   dout(10) << "completed item for ino " << iter->second.ino << dendl;
 
   in_flight.erase(iter);
   logger->set(l_pq_executing, in_flight.size());
+  files_high_water = std::max(files_high_water, in_flight.size());
+  logger->set(l_pq_executing_high_water, files_high_water);
   dout(10) << "in_flight.size() now " << in_flight.size() << dendl;
 
   uint64_t write_pos = journaler.get_write_pos(); 

src/mds/PurgeQueue.h

@@ -85,7 +85,9 @@ enum {
 
   // How many items have been finished by PurgeQueue
   l_pq_executing_ops,
+  l_pq_executing_ops_high_water,
   l_pq_executing,
+  l_pq_executing_high_water,
   l_pq_executed,
   l_pq_item_in_journal,
   l_pq_last
@@ -152,7 +154,7 @@ public:
 
   void handle_conf_change(const std::set<std::string>& changed, const MDSMap& mds_map);
 
-protected:
+private:
   uint32_t _calculate_ops(const PurgeItem &item) const;
 
   bool _can_consume();
@@ -215,5 +217,8 @@ protected:
   std::vector<Context*> waiting_for_recovery;
 
   size_t purge_item_journal_size;
+
+  uint64_t ops_high_water = 0;
+  uint64_t files_high_water = 0;
 };
 #endif