Add info about overhead in heap blocks and OSet nodes.
git-svn-id: svn://svn.valgrind.org/valgrind/trunk@5361 a5019735-40e9-0310-863c-91ae7b9d1cf9
diff --git a/coregrind/m_oset.c b/coregrind/m_oset.c
index 695d45d..0730ac6 100644
--- a/coregrind/m_oset.c
+++ b/coregrind/m_oset.c
@@ -42,7 +42,8 @@
// - First is the AVL metadata, which is three words: a left pointer, a
// right pointer, and a word containing balancing information and a
// "magic" value which provides some checking that the user has not
-// corrupted the metadata.
+// corrupted the metadata. So the overhead is 12 bytes on 32-bit
+// platforms and 24 bytes on 64-bit platforms.
// - Second is the user's data. This can be anything. Note that because it
// comes after the metadata, it will only be word-aligned, even if the
// user data is a struct that would normally be doubleword-aligned.