osd: avoid OSDShardPGSlot allocation in fast path

If the entry already exists, we don't want to construct the PGSlot
and then throw it out.

Signed-off-by: Sage Weil <sage@redhat.com>

diff --git a/src/osd/OSD.cc b/src/osd/OSD.cc
index 5af036a24060286ab9fba2b255b442efe911b0cf..7f503ac56931bafe83958a9e1e7b81a9df5239af 100644 (file)
--- a/src/osd/OSD.cc
+++ b/src/osd/OSD.cc
@@ -9525,9 +9525,10 @@ void OSDShard::_prime_splits(set<spg_t> *pgids)
   while (p != pgids->end()) {
     unsigned shard_index = p->hash_to_shard(osd->num_shards);
     if (shard_index == shard_id) {
-      auto r = pg_slots.emplace(*p, make_unique<OSDShardPGSlot>());
+      auto r = pg_slots.emplace(*p, nullptr);
       if (r.second) {
        dout(10) << "priming slot " << *p << dendl;
+       r.first->second = make_unique<OSDShardPGSlot>();
        r.first->second->waiting_for_split = true;
       } else {
        auto q = r.first;
@@ -9646,7 +9647,10 @@ void OSD::ShardedOpWQ::_process(uint32_t thread_index, heartbeat_handle_d *hb)
     return;    // OSD shutdown, discard.
   }
   const auto token = item.get_ordering_token();
-  auto r = sdata->pg_slots.emplace(token, make_unique<OSDShardPGSlot>());
+  auto r = sdata->pg_slots.emplace(token, nullptr);
+  if (r.second) {
+    r.first->second = make_unique<OSDShardPGSlot>();
+  }
   OSDShardPGSlot *slot = r.first->second.get();
   dout(20) << __func__ << " " << token
           << (r.second ? " (new)" : "")