Update GHC.Stats docs

Make it clear that max_live_bytes is updated after a major GC whereas
live_bytes is updated after all GCs (including minor collections) and
considers data in uncollected generations as live.

Reviewers: bgamari, simonmar, hvr

Reviewed By: bgamari

Subscribers: rwbarton, thomie, carter

Differential Revision: https://phabricator.haskell.org/D4734

1 files changed, 5 insertions, 2 deletions

diff --git a/includes/RtsAPI.h b/includes/RtsAPI.h
index 69ec6075db..79c4d8ef53 100644
--- a/includes/RtsAPI.h
+++ b/includes/RtsAPI.h
@@ -127,7 +127,9 @@ typedef struct GCDetails_ {
   uint32_t threads;
     // Number of bytes allocated since the previous GC
   uint64_t allocated_bytes;
-    // Total amount of live data in the heap (incliudes large + compact data)
+    // Total amount of live data in the heap (incliudes large + compact data).
+    // Updated after every GC. Data in uncollected generations (in minor GCs)
+    // are considered live.
   uint64_t live_bytes;
     // Total amount of live data in large objects
   uint64_t large_objects_bytes;
@@ -165,7 +167,8 @@ typedef struct _RTSStats {
   uint32_t major_gcs;
     // Total bytes allocated
   uint64_t allocated_bytes;
-    // Maximum live data (including large objects + compact regions)
+    // Maximum live data (including large objects + compact regions) in the
+    // heap. Updated after a major GC.
   uint64_t max_live_bytes;
     // Maximum live data in large objects
   uint64_t max_large_objects_bytes;