osd, PG: share the snaptrimq.size() within pg_stat_t

That way it will be unnecessary to go through all pgs separately
to find pgs with excessively long snap trim queues. And we don't need
to share snap trim queues itself, which may be large by itself.
As snap trim queues tend to be short and anything above 50 000
I consider absurdly large, the snaptrimq_len is capped at 2^32 to
save space in pg_stat_t.

Signed-off-by: Piotr Dałek <piotr.dalek@corp.ovh.com>

diff --git a/src/mon/PGMap.cc b/src/mon/PGMap.cc
index c5107af996c7fd0e2f9fa7bfd0b8198c376b7bae..4afa37826a9ec1aec2bc6e63b9ecacaaafe3e06c 100644 (file)
--- a/src/mon/PGMap.cc
+++ b/src/mon/PGMap.cc
@@ -1479,6 +1479,7 @@ void PGMap::dump_pg_stats_plain(
     tab.define_column("SCRUB_STAMP", TextTable::LEFT, TextTable::RIGHT);
     tab.define_column("LAST_DEEP_SCRUB", TextTable::LEFT, TextTable::RIGHT);
     tab.define_column("DEEP_SCRUB_STAMP", TextTable::LEFT, TextTable::RIGHT);
+    tab.define_column("SNAPTRIMQ_LEN", TextTable::LEFT, TextTable::RIGHT);
   }
 
   for (auto i = pg_stats.begin();
@@ -1517,6 +1518,7 @@ void PGMap::dump_pg_stats_plain(
           << st.last_scrub_stamp
           << st.last_deep_scrub
           << st.last_deep_scrub_stamp
+          << st.snaptrimq_len
           << TextTable::endrow;
     }
   }

diff --git a/src/osd/PG.cc b/src/osd/PG.cc
index 402a9d7c65b9091931e9796e077a28f7f8bbf598..19b3ac6a92e8cb74ce9e9df5f4396d53decb1be1 100644 (file)
--- a/src/osd/PG.cc
+++ b/src/osd/PG.cc
@@ -2668,6 +2668,7 @@ void PG::_update_calc_stats()
   info.stats.ondisk_log_size = info.stats.log_size;
   info.stats.log_start = pg_log.get_tail();
   info.stats.ondisk_log_start = pg_log.get_tail();
+  info.stats.snaptrimq_len = snap_trimq.size();
 
   // If actingset is larger then upset we will have misplaced,
   // so we will report based on actingset size.

diff --git a/src/osd/osd_types.cc b/src/osd/osd_types.cc
index e8599f92197a8dbe2c3bc987e469cd509b12bcbe..d0031ff7783d9742fcbeb353d8f3961cde4d1306 100644 (file)
--- a/src/osd/osd_types.cc
+++ b/src/osd/osd_types.cc
@@ -2319,6 +2319,7 @@ void pg_stat_t::dump(Formatter *f) const
   f->dump_bool("hitset_stats_invalid", hitset_stats_invalid);
   f->dump_bool("hitset_bytes_stats_invalid", hitset_bytes_stats_invalid);
   f->dump_bool("pin_stats_invalid", pin_stats_invalid);
+  f->dump_unsigned("snaptrimq_len", snaptrimq_len);
   stats.dump(f);
   f->open_array_section("up");
   for (vector<int32_t>::const_iterator p = up.begin(); p != up.end(); ++p)
@@ -2364,7 +2365,7 @@ void pg_stat_t::dump_brief(Formatter *f) const
 
 void pg_stat_t::encode(bufferlist &bl) const
 {
-  ENCODE_START(24, 22, bl);
+  ENCODE_START(25, 22, bl);
   ::encode(version, bl);
   ::encode(reported_seq, bl);
   ::encode(reported_epoch, bl);
@@ -2407,6 +2408,7 @@ void pg_stat_t::encode(bufferlist &bl) const
   ::encode(pin_stats_invalid, bl);
   ::encode(state, bl);
   ::encode(purged_snaps, bl);
+  ::encode(snaptrimq_len, bl);
   ENCODE_FINISH(bl);
 }
 
@@ -2468,6 +2470,9 @@ void pg_stat_t::decode(bufferlist::iterator &bl)
   }
   if (struct_v >= 24) {
     ::decode(purged_snaps, bl);
+    if (struct_v >= 25) {
+      ::decode(snaptrimq_len, bl);
+    }
   }
   DECODE_FINISH(bl);
 }
@@ -2500,6 +2505,7 @@ void pg_stat_t::generate_test_instances(list<pg_stat_t*>& o)
   a.last_deep_scrub = eversion_t(13, 14);
   a.last_deep_scrub_stamp = utime_t(15, 16);
   a.last_clean_scrub_stamp = utime_t(17, 18);
+  a.snaptrimq_len = 1048576;
   list<object_stat_collection_t*> l;
   object_stat_collection_t::generate_test_instances(l);
   a.stats = *l.back();
@@ -2563,7 +2569,8 @@ bool operator==(const pg_stat_t& l, const pg_stat_t& r)
     l.up_primary == r.up_primary &&
     l.acting_primary == r.acting_primary &&
     l.pin_stats_invalid == r.pin_stats_invalid &&
-    l.purged_snaps == r.purged_snaps;
+    l.purged_snaps == r.purged_snaps &&
+    l.snaptrimq_len == r.snaptrimq_len;
 }
 
 // -- pool_stat_t --

diff --git a/src/osd/osd_types.h b/src/osd/osd_types.h
index bc491dea25926676f7954ac52e7b1ee89d725f77..d3d866019ae42eed5fb26a2d04a8a537d3d8caa3 100644 (file)
--- a/src/osd/osd_types.h
+++ b/src/osd/osd_types.h
@@ -1963,6 +1963,10 @@ struct pg_stat_t {
   int32_t up_primary;
   int32_t acting_primary;
 
+  // snaptrimq.size() is 64bit, but let's be serious - anything over 50k is
+  // absurd already, so cap it to 2^32 and save 4 bytes at  the same time
+  uint32_t snaptrimq_len;
+
   bool stats_invalid:1;
   /// true if num_objects_dirty is not accurate (because it was not
   /// maintained starting from pool creation)
@@ -1982,6 +1986,7 @@ struct pg_stat_t {
       mapping_epoch(0),
       up_primary(-1),
       acting_primary(-1),
+      snaptrimq_len(0),
       stats_invalid(false),
       dirty_stats_invalid(false),
       omap_stats_invalid(false),
@@ -2010,17 +2015,29 @@ struct pg_stat_t {
       log_size = f;
     if (ondisk_log_size < f)
       ondisk_log_size = f;
+    if (snaptrimq_len < f)
+      snaptrimq_len = f;
   }
 
   void add(const pg_stat_t& o) {
     stats.add(o.stats);
     log_size += o.log_size;
     ondisk_log_size += o.ondisk_log_size;
+    if (((uint64_t)snaptrimq_len + (uint64_t)o.snaptrimq_len) > (uint64_t)(1 << 31)) {
+      snaptrimq_len = 1 << 31;
+    } else {
+      snaptrimq_len += o.snaptrimq_len;
+    }
   }
   void sub(const pg_stat_t& o) {
     stats.sub(o.stats);
     log_size -= o.log_size;
     ondisk_log_size -= o.ondisk_log_size;
+    if (o.snaptrimq_len < snaptrimq_len) {
+      snaptrimq_len -= o.snaptrimq_len;
+    } else {
+      snaptrimq_len = 0;
+    }
   }
 
   bool is_acting_osd(int32_t osd, bool primary) const;