Amend latest note.

1 files changed, 11 insertions, 7 deletions

diff --git a/notes/260922-use-alloc-3.md b/notes/260922-use-alloc-3.md
index 9ca98f7..abe520d 100644
--- a/notes/260922-use-alloc-3.md
+++ b/notes/260922-use-alloc-3.md
@@ -65,13 +65,17 @@ Block Alloc, with the following collection strategy:
   phase (bit was set in original) but have been found not to be live
   anymore (bit not set in new).
 
-* If an entire block comes out empty, we can release it directly back
-  to Meta Alloc.  Otherwise, we perform a `free()` on individual "now
-  dead" memory slots which does something similar to Block Alloc, but
-  freeing directly to the shared free-list of the appropriate size
-  class, instead of thread-local caches.  The mutator threads have
-  thread-local caches anyway, filled from the global free-list in
-  chunks, as an optimization.
+* If a block was completely full, but is now completely empty, we can
+  free it back to Meta Alloc.  (If only some slots were occupied and
+  now the whole block is empty, we can't free it, since some of its
+  unoccupied slots may be in a free-list.)
+
+* Otherwise, we `free()` individual "now dead" memory slots in it,
+  which works similarly to the `free()` of Block Alloc, but putting
+  the slots directly into the shared free-list of the size class, in
+  chunks to decrease contention.  (Mutator threads have thread-local
+  caches anyway, filled from the global free-list in chunks, as an
+  optimization.)
 
 * We need a way to identify what size class a block is for.  Remember
   that the blocks supporting multiple size classes use a `u32` but