os/bluestore: pack a few more in-memory types

src/os/bluestore/BlueStore.cc

@@ -1043,29 +1043,28 @@ void BlueStore::BufferSpace::finish_write(uint64_t seq)
 {
   std::lock_guard<std::recursive_mutex> l(cache->lock);
 
-  auto i = writing_map.begin();
-  while (i != writing_map.end()) {
-    if (i->first > seq)
+  auto i = writing.begin();
+  while (i != writing.end()) {
+    if (i->seq > seq) {
       break;
+    }
+    if (i->seq < seq) {
+      ++i;
+      continue;
+    }
 
-    auto l = i->second.begin();
-    while (l != i->second.end()) {
-      Buffer *b = &*l;
-      dout(20) << __func__ << " " << *b << dendl;
-      assert(b->is_writing());
+    Buffer *b = &*i;
+    dout(20) << __func__ << " " << *b << dendl;
+    assert(b->is_writing());
 
-      if (b->flags & Buffer::FLAG_NOCACHE) {
-        i->second.erase(l++);
-        buffer_map.erase(b->offset);
-      } else {
-        b->state = Buffer::STATE_CLEAN;
-        i->second.erase(l++);
-        cache->_add_buffer(b, 1, nullptr);
-      }
+    if (b->flags & Buffer::FLAG_NOCACHE) {
+      writing.erase(i++);
+      buffer_map.erase(b->offset);
+    } else {
+      b->state = Buffer::STATE_CLEAN;
+      writing.erase(i++);
+      cache->_add_buffer(b, 1, nullptr);
     }
-
-    assert(i->second.empty());
-    writing_map.erase(i++);
   }
 
   cache->_audit("finish_write end");

src/os/bluestore/BlueStore.h

@@ -147,16 +147,16 @@ class BlueStore : public ObjectStore,
     uint16_t cache_private = 0; ///< opaque (to us) value used by Cache impl
     uint32_t flags;             ///< FLAG_*
     uint64_t seq;
-    uint64_t offset, length;
+    uint32_t offset, length;
     bufferlist data;
 
     boost::intrusive::list_member_hook<> lru_item;
     boost::intrusive::list_member_hook<> state_item;
 
-    Buffer(BufferSpace *space, unsigned s, uint64_t q, uint64_t o, uint64_t l,
+    Buffer(BufferSpace *space, unsigned s, uint64_t q, uint32_t o, uint32_t l,
 	   unsigned f = 0)
       : space(space), state(s), flags(f), seq(q), offset(o), length(l) {}
-    Buffer(BufferSpace *space, unsigned s, uint64_t q, uint64_t o, bufferlist& b,
+    Buffer(BufferSpace *space, unsigned s, uint64_t q, uint32_t o, bufferlist& b,
 	   unsigned f = 0)
       : space(space), state(s), flags(f), seq(q), offset(o),
 	length(b.length()), data(b) {}
@@ -171,11 +171,11 @@ class BlueStore : public ObjectStore,
       return state == STATE_WRITING;
     }
 
-    uint64_t end() const {
+    uint32_t end() const {
       return offset + length;
     }
 
-    void truncate(uint64_t newlen) {
+    void truncate(uint32_t newlen) {
       assert(newlen < length);
       if (data.length()) {
 	bufferlist t;
@@ -207,7 +207,11 @@ class BlueStore : public ObjectStore,
 
     map<uint64_t,std::unique_ptr<Buffer>> buffer_map;
     Cache *cache;
-    map<uint64_t, state_list_t> writing_map;
+
+    // we use a bare intrusive list here instead of std::map because
+    // it uses less memory and we expect this to be very small (very
+    // few IOs in flight to the same Blob at the same time).
+    state_list_t writing;   ///< writing buffers, sorted by seq, ascending
 
     BufferSpace(Cache *c) : cache(c) {
       if (cache) {
@@ -216,7 +220,7 @@ class BlueStore : public ObjectStore,
     }
     ~BufferSpace() {
       assert(buffer_map.empty());
-      assert(writing_map.empty());
+      assert(writing.empty());
       if (cache) {
 	cache->rm_blob();
       }
@@ -226,7 +230,7 @@ class BlueStore : public ObjectStore,
       cache->_audit("_add_buffer start");
       buffer_map[b->offset].reset(b);
       if (b->is_writing()) {
-        writing_map[b->seq].push_back(*b);
+        writing.push_back(*b);
       } else {
 	cache->_add_buffer(b, level, near);
       }
@@ -238,12 +242,7 @@ class BlueStore : public ObjectStore,
     void _rm_buffer(map<uint64_t,std::unique_ptr<Buffer>>::iterator p) {
       cache->_audit("_rm_buffer start");
       if (p->second->is_writing()) {
-        uint64_t seq = (*p->second.get()).seq;
-        auto it = writing_map.find(seq);
-        assert(it != writing_map.end());
-        it->second.erase(it->second.iterator_to(*p->second));
-        if (it->second.empty())
-          writing_map.erase(it);
+        writing.erase(writing.iterator_to(*p->second));
       } else {
 	cache->_rm_buffer(p->second.get());
       }
@@ -318,15 +317,15 @@ class BlueStore : public ObjectStore,
   struct SharedBlob : public boost::intrusive::unordered_set_base_hook<> {
     std::atomic_int nref = {0}; ///< reference count
 
+    // these are defined/set if the shared_blob is 'loaded'
+    bool loaded = false;        ///< whether shared_blob_t is loaded
+    bluestore_shared_blob_t shared_blob; ///< the actual shared state
+
     // these are defined/set if the blob is marked 'shared'
     uint64_t sbid = 0;          ///< shared blob id
     string key;                 ///< key in kv store
     SharedBlobSet *parent_set = 0;  ///< containing SharedBlobSet
 
-    // these are defined/set if the shared_blob is 'loaded'
-    bluestore_shared_blob_t shared_blob; ///< the actual shared state
-    bool loaded = false;        ///< whether shared_blob_t is loaded
-
     BufferSpace bc;             ///< buffer cache
 
     SharedBlob(uint64_t i, const string& k, Cache *c);
@@ -407,15 +406,13 @@ class BlueStore : public ObjectStore,
   /// in-memory blob metadata and associated cached buffers (if any)
   struct Blob : public boost::intrusive::set_base_hook<> {
     std::atomic_int nref = {0};     ///< reference count
-    int id = -1;                    ///< id, for spanning blobs only, >= 0
+    int16_t id = -1;                ///< id, for spanning blobs only, >= 0
+    int16_t last_encoded_id = -1;   ///< (ephemeral) used during encoding only
     SharedBlobRef shared_blob;      ///< shared blob state (if any)
 
     /// refs from this shard.  ephemeral if id<0, persisted if spanning.
     bluestore_extent_ref_map_t ref_map;
 
-
-    int last_encoded_id = -1;       ///< (ephemeral) used during encoding only
-
   private:
     mutable bluestore_blob_t blob;  ///< decoded blob metadata
     mutable bool dirty = true;      ///< true if blob is newer than blob_bl

src/test/objectstore/test_bluestore_types.cc

@@ -26,6 +26,9 @@ TEST(bluestore, sizeof) {
   P(BlueStore::extent_map_t);
   P(BlueStore::blob_map_t);
   P(BlueStore::BufferSpace);
+  P(BlueStore::Buffer);
+  P(bluestore_onode_t);
+  P(bluestore_blob_t);
   P(bluestore_extent_ref_map_t);
   P(bluestore_extent_ref_map_t::record_t);
   P(std::atomic_int);