[pypy-svn] r47805 - pypy/dist/pypy/rpython/memory/gc

[arigo at codespeak.net]

Author: arigo
Date: Wed Oct 24 11:38:36 2007
New Revision: 47805

Modified:
   pypy/dist/pypy/rpython/memory/gc/base.py
   pypy/dist/pypy/rpython/memory/gc/generation.py
   pypy/dist/pypy/rpython/memory/gc/semispace.py
Log:
Implement a "red zone" mechanism in the semispace GC to double the
space size before it is completely full.


Modified: pypy/dist/pypy/rpython/memory/gc/base.py
==============================================================================
--- pypy/dist/pypy/rpython/memory/gc/base.py	(original)
+++ pypy/dist/pypy/rpython/memory/gc/base.py	Wed Oct 24 11:38:36 2007
@@ -5,6 +5,7 @@
     _alloc_flavor_ = "raw"
     moving_gc = False
     needs_write_barrier = False
+    needs_zero_gc_pointers = True
 
     def set_query_functions(self, is_varsize, getfinalizer,
                             offsets_to_gc_pointers,

Modified: pypy/dist/pypy/rpython/memory/gc/generation.py
==============================================================================
--- pypy/dist/pypy/rpython/memory/gc/generation.py	(original)
+++ pypy/dist/pypy/rpython/memory/gc/generation.py	Wed Oct 24 11:38:36 2007
@@ -4,6 +4,7 @@
 from pypy.rpython.lltypesystem.llmemory import NULL, raw_malloc_usage
 from pypy.rpython.lltypesystem import lltype, llmemory, llarena
 from pypy.rlib.objectmodel import free_non_gc_object, debug_assert
+from pypy.rpython.lltypesystem.lloperation import llop
 
 # The following flag is never set on young objects, i.e. the ones living
 # in the nursery.  It is initially set on all prebuilt and old objects,
@@ -148,6 +149,7 @@
             debug_assert(self.nursery_size <= self.top_of_space - self.free,
                          "obtain_free_space failed to do its job")
         if self.nursery:
+            #llop.debug_print(lltype.Void, "minor collect")
             # a nursery-only collection
             scan = self.free
             self.collect_oldrefs_to_nursery()

Modified: pypy/dist/pypy/rpython/memory/gc/semispace.py
==============================================================================
--- pypy/dist/pypy/rpython/memory/gc/semispace.py	(original)
+++ pypy/dist/pypy/rpython/memory/gc/semispace.py	Wed Oct 24 11:38:36 2007
@@ -20,6 +20,7 @@
 class SemiSpaceGC(MovingGCBase):
     _alloc_flavor_ = "raw"
     inline_simple_malloc = True
+    needs_zero_gc_pointers = False
 
     HDR = lltype.Struct('header', ('forw', llmemory.Address),
                                   ('tid', lltype.Signed))
@@ -45,6 +46,7 @@
         self.run_finalizers = self.AddressLinkedList()
         self.objects_with_weakrefs = self.AddressLinkedList()
         self.finalizer_lock_count = 0
+        self.red_zone = 0
 
     def disable_finalizers(self):
         self.finalizer_lock_count += 1
@@ -109,7 +111,11 @@
     def try_obtain_free_space(self, needed):
         # XXX for bonus points do big objects differently
         needed = raw_malloc_usage(needed)
-        self.semispace_collect()
+        if (self.red_zone >= 2 and self.space_size < self.max_space_size and
+            self.double_space_size()):
+            pass    # collect was done during double_space_size()
+        else:
+            self.semispace_collect()
         missing = needed - (self.top_of_space - self.free)
         if missing <= 0:
             return True      # success
@@ -133,6 +139,7 @@
             return True
 
     def double_space_size(self):
+        self.red_zone = 0
         old_fromspace = self.fromspace
         newsize = self.space_size * 2
         newspace = llarena.arena_malloc(newsize, True)
@@ -192,7 +199,24 @@
         self.notify_objects_just_moved()
         if not size_changing:
             llarena.arena_reset(fromspace, self.space_size, True)
+            self.record_red_zone()
             self.execute_finalizers()
+        #llop.debug_print(lltype.Void, 'collected', self.space_size, size_changing, self.top_of_space - self.free)
+
+    def record_red_zone(self):
+        # red zone: if the space is more than 80% full, the next collection
+        # should double its size.  If it is more than 66% full twice in a row,
+        # then it should double its size too.  (XXX adjust)
+        # The goal is to avoid many repeated collection that don't free a lot
+        # of memory each, if the size of the live object set is just below the
+        # size of the space.
+        free_after_collection = self.top_of_space - self.free
+        if free_after_collection > self.space_size // 3:
+            self.red_zone = 0
+        else:
+            self.red_zone += 1
+            if free_after_collection < self.space_size // 5:
+                self.red_zone += 1
 
     def scan_copied(self, scan):
         while scan < self.free: