Nicholas Nethercote 6373d8547c Bug 1252375 - Fix up jemalloc stats reporting. r=erahm.
We have some oddities in our jemalloc stats reporting.

- "heap-overhead-ratio" is a strange measurement: overhead / non-overhead,
  expressed as a percentage. And it omits "bin_unused", which appears to be an
  oversight.

- "heap-committed" also omits "bin_unused".

- There are some minor errors in memory report descriptions.

This patch fixes these and improves the heap reporting. It makes the following
reporting changes:

- "heap-allocated": Duplicated as "heap-committed/allocated". (We keep
  "heap-allocated" because that's a special value used in the computation of
  "heap-unclassified".)

- "heap-committed/overhead": Added; it's the same as the sum of the
  "explicit/heap-overhead/*" values. Together with "heap-committed/allocated"
  it shows clearly what fraction of the heap is overhead and what fraction is
  useful.

- "heap-committed": Removed; now implicit as the "heap-committed/" node.

- "heap-overhead-ratio":
  - Removed from memory reports; now shown as the percentage of the new
    "heap-committed/overhead" node.
  - Still available as a distinguished amount (because it's useful in
    isolation) but renamed to heapOverheadFraction, and the telemetry ID is
    renamed as MEMORY_HEAP_OVERHEAD_FRACTION.

- "heap-chunks": Removed; it's not that interesting, and can be manually
  computed as "heap-mapped" / "heap-chunksize" if necessary.

--HG--
extra : rebase_source : 6f238cda780eb17b2de2f8b9a0b04377c93b109c
2016-03-03 12:49:27 +11:00
..