* Author:
* Paolo Molaro (lupus@ximian.com)
*
- * Copyright (C) 2005-2006 Novell, Inc
+ * Copyright 2005-2009 Novell, Inc (http://www.novell.com)
*
* Thread start/stop adapted from Boehm's GC:
* Copyright (c) 1994 by Xerox Corporation. All rights reserved.
}
*/
-#define MAX_DEBUG_LEVEL 9
+#define MAX_DEBUG_LEVEL 8
#define DEBUG(level,a) do {if (G_UNLIKELY ((level) <= MAX_DEBUG_LEVEL && (level) <= gc_debug_level)) a;} while (0)
#define TV_DECLARE(name) struct timeval name
/*
* used when moving the objects
* When the nursery is collected, objects are copied to to_space.
- * The area between to_space and gray_objects is used as a stack
+ * The area between gray_first and gray_objects is used as a stack
* of objects that need their fields checked for more references
* to be copied.
* We should optimize somehow this mechanism to avoid rescanning
* test cache misses and other graph traversal orders.
*/
static char *to_space = NULL;
+static char *gray_first = NULL;
static char *gray_objects = NULL;
static char *to_space_end = NULL;
static GCMemSection *to_space_section = NULL;
return NULL;
}
+/*
+ * drain_gray_stack:
+ *
+ * Scan objects in the gray stack until the stack is empty. This should be called
+ * frequently after each object is copied, to achieve better locality and cache
+ * usage.
+ */
+static void inline
+drain_gray_stack (char *start_addr, char *end_addr)
+{
+ char *gray_start = gray_first;
+
+ while (gray_start < gray_objects) {
+ DEBUG (9, fprintf (gc_debug_file, "Precise gray object scan %p (%s)\n", gray_start, safe_name (gray_start)));
+ gray_start = scan_object (gray_start, start_addr, end_addr);
+ }
+
+ gray_first = gray_start;
+}
+
/*
* scan_vtype:
*
while (desc) {
if ((desc & 1) && *start_root) {
*start_root = copy_object (*start_root, n_start, n_end);
- DEBUG (9, fprintf (gc_debug_file, "Overwrote root at %p with %p\n", start_root, *start_root)); \
+ DEBUG (9, fprintf (gc_debug_file, "Overwrote root at %p with %p\n", start_root, *start_root));
+ drain_gray_stack (n_start, n_end);
}
desc >>= 1;
start_root++;
if ((bmap & 1) && *objptr) {
*objptr = copy_object (*objptr, n_start, n_end);
DEBUG (9, fprintf (gc_debug_file, "Overwrote root at %p with %p\n", objptr, *objptr));
+ drain_gray_stack (n_start, n_end);
}
bmap >>= 1;
++objptr;
}
static void
-drain_gray_stack (char *start_addr, char *end_addr)
+finish_gray_stack (char *start_addr, char *end_addr)
{
TV_DECLARE (atv);
TV_DECLARE (btv);
* We need to walk the LO list as well in search of marked big objects
* (use a flag since this is needed only on major collections). We need to loop
* here as well, so keep a counter of marked LO (increasing it in copy_object).
+ * To achieve better cache locality and cache usage, we drain the gray stack
+ * frequently, after each object is copied, and just finish the work here.
*/
- TV_GETTIME (btv);
- gray_start = to_space;
- DEBUG (6, fprintf (gc_debug_file, "Precise scan of gray area: %p-%p, size: %d\n", gray_start, gray_objects, (int)(gray_objects - gray_start)));
+ gray_start = gray_first;
while (gray_start < gray_objects) {
DEBUG (9, fprintf (gc_debug_file, "Precise gray object scan %p (%s)\n", gray_start, safe_name (gray_start)));
gray_start = scan_object (gray_start, start_addr, end_addr);
}
TV_GETTIME (atv);
- DEBUG (2, fprintf (gc_debug_file, "Gray stack scan: %d usecs\n", TV_ELAPSED (btv, atv)));
//scan_old_generation (start_addr, end_addr);
DEBUG (2, fprintf (gc_debug_file, "Old generation done\n"));
/* walk the finalization queue and move also the objects that need to be
* We reset to_space if we allocated objects in degraded mode.
*/
if (to_space_section)
- to_space = gray_objects = to_space_section->next_data;
+ to_space = gray_objects = gray_first = to_space_section->next_data;
if ((to_space_end - to_space) < max_garbage_amount) {
section = alloc_section (nursery_section->size * 4);
g_assert (nursery_section->size >= max_garbage_amount);
- to_space = gray_objects = section->next_data;
+ to_space = gray_objects = gray_first = section->next_data;
to_space_end = section->end_data;
to_space_section = section;
}
TV_GETTIME (btv);
DEBUG (2, fprintf (gc_debug_file, "Root scan: %d usecs\n", TV_ELAPSED (atv, btv)));
- drain_gray_stack (nursery_start, nursery_next);
+ finish_gray_stack (nursery_start, nursery_next);
/* walk the pin_queue, build up the fragment list of free memory, unmark
* pinned objects as we go, memzero() the empty fragments so they are ready for the
/* allocate the big to space */
DEBUG (4, fprintf (gc_debug_file, "Allocate tospace for size: %zd\n", copy_space_required));
section = alloc_section (copy_space_required);
- to_space = gray_objects = section->next_data;
+ to_space = gray_objects = gray_first = section->next_data;
to_space_end = section->end_data;
to_space_section = section;
/* we need to go over the big object list to see if any was marked and scan it
* And we need to make this in a loop, considering that objects referenced by finalizable
- * objects could reference big objects (this happens in drain_gray_stack ())
+ * objects could reference big objects (this happens in finish_gray_stack ())
*/
scan_needed_big_objects (heap_start, heap_end);
/* all the objects in the heap */
- drain_gray_stack (heap_start, heap_end);
+ finish_gray_stack (heap_start, heap_end);
/* sweep the big objects list */
prevbo = NULL;
projects / mono.git / blobdiff