From: Guang Yang <yguang@yahoo-inc.com>
Date: Tue, 10 Mar 2015 07:06:09 +0000 (+0000)
Subject: osd : populate the needs_recovery_map source fast when only one peer has missing
X-Git-Tag: v9.0.1~45^2
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=12f564509b951c9c8134c21d09a12f0c06ac95c8;p=ceph.git

osd : populate the needs_recovery_map source fast when only one peer has missing

The most common case for peering, is that one OSD/host get down for some time, and
the OSD(s) are still in. Once bring them up again, the primary OSD need to populate
the recovery map and add the recovery source. If there are N replicas, M missing objects,
the current complexity of the routine is N*M*logN.

This patch detects if there is only one peers has missing, it goes through a fast routine
add populate the map with complexity of N*logN.

Fixes: 9558

Signed-off-by: Guang Yang <yguang@yahoo-inc.com>
---

diff --git a/src/osd/PG.cc b/src/osd/PG.cc
index 7447ecca9638..566bd1fb459d 100644
--- a/src/osd/PG.cc
+++ b/src/osd/PG.cc
@@ -453,6 +453,18 @@ bool PG::MissingLoc::readable_with_acting(
   return (*is_readable)(have_acting);
 }
 
+void PG::MissingLoc::add_batch_sources_info(
+  const set<pg_shard_t> &sources)
+{
+  dout(10) << __func__ << ": adding sources in batch " << sources.size() << dendl;
+  for (map<hobject_t, pg_missing_t::item>::const_iterator i = needs_recovery_map.begin(); 
+      i != needs_recovery_map.end();
+      ++i) {
+    missing_loc[i->first].insert(sources.begin(), sources.end());
+    missing_loc_sources.insert(sources.begin(), sources.end());
+    }
+}
+
 bool PG::MissingLoc::add_source_info(
   pg_shard_t fromosd,
   const pg_info_t &oinfo,
@@ -1652,14 +1664,19 @@ void PG::activate(ObjectStore::Transaction& t,
     }
 
     // Set up missing_loc
+    set<pg_shard_t> complete_shards;
     for (set<pg_shard_t>::iterator i = actingbackfill.begin();
 	 i != actingbackfill.end();
 	 ++i) {
       if (*i == get_primary()) {
-	missing_loc.add_active_missing(pg_log.get_missing());
+	missing_loc.add_active_missing(missing);
+        if (!missing.have_missing())
+          complete_shards.insert(*i);
       } else {
 	assert(peer_missing.count(*i));
 	missing_loc.add_active_missing(peer_missing[*i]);
+        if (!peer_missing[*i].have_missing() && peer_info[*i].last_backfill == hobject_t::get_max())
+          complete_shards.insert(*i);
       }
     }
     // If necessary, create might_have_unfound to help us find our unfound objects.
@@ -1667,19 +1684,27 @@ void PG::activate(ObjectStore::Transaction& t,
     // past intervals.
     might_have_unfound.clear();
     if (needs_recovery()) {
-      missing_loc.add_source_info(pg_whoami, info, pg_log.get_missing(), ctx->handle);
-      for (set<pg_shard_t>::iterator i = actingbackfill.begin();
-	   i != actingbackfill.end();
-	   ++i) {
-	if (*i == pg_whoami) continue;
-	dout(10) << __func__ << ": adding " << *i << " as a source" << dendl;
-	assert(peer_missing.count(*i));
-	assert(peer_info.count(*i));
-	missing_loc.add_source_info(
-	  *i,
-	  peer_info[*i],
-	  peer_missing[*i],
-          ctx->handle);
+      // If only one shard has missing, we do a trick to add all others as recovery
+      // source, this is considered safe since the PGLogs have been merged locally,
+      // and covers vast majority of the use cases, like one OSD/host is down for
+      // a while for hardware repairing
+      if (complete_shards.size() + 1 == actingbackfill.size()) {
+        missing_loc.add_batch_sources_info(complete_shards);
+      } else {
+        missing_loc.add_source_info(pg_whoami, info, pg_log.get_missing(), ctx->handle);
+        for (set<pg_shard_t>::iterator i = actingbackfill.begin();
+	     i != actingbackfill.end();
+	     ++i) {
+	  if (*i == pg_whoami) continue;
+	  dout(10) << __func__ << ": adding " << *i << " as a source" << dendl;
+	  assert(peer_missing.count(*i));
+	  assert(peer_info.count(*i));
+	  missing_loc.add_source_info(
+	    *i,
+	    peer_info[*i],
+	    peer_missing[*i],
+            ctx->handle);
+        }
       }
       for (map<pg_shard_t, pg_missing_t>::iterator i = peer_missing.begin();
 	   i != peer_missing.end();
diff --git a/src/osd/PG.h b/src/osd/PG.h
index 870fdf22e263..abcbe1b80055 100644
--- a/src/osd/PG.h
+++ b/src/osd/PG.h
@@ -442,6 +442,11 @@ public:
       ThreadPool::TPHandle* handle  ///< [in] ThreadPool handle
       ); ///< @return whether a new object location was discovered
 
+    /// Adds recovery sources in batch
+    void add_batch_sources_info(
+      const set<pg_shard_t> &sources  ///< [in] a set of resources which can be used for all objects
+      );
+
     /// Uses osdmap to update structures for now down sources
     void check_recovery_sources(const OSDMapRef osdmap);