Author: Gregor Wegberg <c...@gregorwegberg.com>
Branch: gc-incminimark-pinning-improve
Changeset: r76525:2f78e998eec4
Date: 2015-03-23 11:21 +0100
http://bitbucket.org/pypy/pypy/changeset/2f78e998eec4/
Log: improve comment a bit more
diff --git a/rpython/memory/gc/incminimark.py b/rpython/memory/gc/incminimark.py
--- a/rpython/memory/gc/incminimark.py
+++ b/rpython/memory/gc/incminimark.py
@@ -704,21 +704,33 @@
if self.nursery_barriers.non_empty():
# Pinned object in front of nursery_top. Try reserving
totalsize
# by jumping into the next, yet unused, area inside the
- # nursery. 'Next area' is in this case the space inside the
- # nursery between the next pinned object and the one after that
- # or the end of the nursery. Graphically explained:
+ # nursery. "Next area" in this case is the space between the
+ # pinned object in front of nusery_top and the pinned object
+ # after that. Graphically explained:
#
# |- allocating totalsize failed in this area
- # v v- next pinned object, jump over this one
- # +---------+--------+--------+--------+-----------+
- # | unknown | pinned | empty | pinned | empty | <- nursery
- # +---------+--------+--------+--------+-----------+
- # ^- try reserving totalsize in here next
+ # | |- nursery_top
+ # | | |- pinned object in front of nursery_top,
+ # v v v jump over this
+ # +---------+--------+--------+--------+-----------+ }
+ # | used | pinned | empty | pinned | empty | }- nursery
+ # +---------+--------+--------+--------+-----------+ }
+ # ^- try reserving totalsize in here next
#
+ # All pinned objects are represented by entries in
+ # nursery_barriers (see minor_collection). The last entry is
+ # always the end of the nursery. Therefore if nursery_barriers
+ # contains only one element, we jump over a pinned object and
+ # the "next area" (the space where we will try to allocate
+ # totalsize) starts at the end of the pinned object and ends at
+ # nursery's end.
+ #
+ # find the size of the pinned object after nursery_top
size_gc_header = self.gcheaderbuilder.size_gc_header
pinned_obj_size = size_gc_header + self.get_size(
self.nursery_top + size_gc_header)
#
+ # update used nursery space to allocate objects
self.nursery_free = self.nursery_top + pinned_obj_size
self.nursery_top = self.nursery_barriers.popleft()
else:
@@ -1645,7 +1657,9 @@
else:
llarena.arena_reset(prev, self.nursery + self.nursery_size - prev,
0)
#
+ # always add the end of the nursery to the list
nursery_barriers.append(self.nursery + self.nursery_size)
+ #
self.nursery_barriers = nursery_barriers
self.surviving_pinned_objects.delete()
#
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