Total:      14.90s     15.31s (flat, cum) 32.93%
...
   2331         50ms       50ms           func (s *memSeries) append(t int64, v float64, appendID uint64, chunkDiskMapper *chunks.ChunkDiskMapper) (sampleInOrder, chunkCreated bool) { 
...
   2337            .       70ms           	c := s.head() 
   2338            .          .            
   2339        6.27s      6.27s           	if c == nil { 
   2340        4.22s      4.28s           		if len(s.mmappedChunks) > 0 && s.mmappedChunks[len(s.mmappedChunks)-1].maxTime >= t { 
   2341            .          .           			// Out of order sample. Sample timestamp is already in the mmaped chunks, so ignore it. 
   2342        4.31s      4.31s           			return false, false 
   2343            .          .           		} 
   2344            .          .           		// There is no chunk in this series yet, create the first chunk for the sample. 
   2345            .      120ms           		c = s.cutNewHeadChunk(t, chunkDiskMapper) 
   2346            .       10ms           		chunkCreated = true 
   2347            .          .           	}