This was the case a few years back when the fastest pools were implemented with recursive data structures (e.g. linked lists for the freelists in gperftools).
In the new tcmalloc (and, I think, hoard?) the fastest pools are essentially slabs with bump allocation, so the fastest (and by far, the most common) calls are a grand total of 15 or so instructions, without many cache misses (size class lookups tend to stay in the cache). Call overhead can be a substantial chunk of that.
In the new tcmalloc (and, I think, hoard?) the fastest pools are essentially slabs with bump allocation, so the fastest (and by far, the most common) calls are a grand total of 15 or so instructions, without many cache misses (size class lookups tend to stay in the cache). Call overhead can be a substantial chunk of that.