Experimental "mark-region" strategy for the old generation

Sometimes better than the default copying, enabled by +RTS -w

3 files changed, 11 insertions, 3 deletions

diff --git a/includes/Block.h b/includes/Block.h
index e2e691ab0e..3d7a5c8a86 100644
--- a/includes/Block.h
+++ b/includes/Block.h
@@ -84,12 +84,15 @@ typedef struct bdescr_ {
 #define BF_LARGE     2
 /* Block is pinned */
 #define BF_PINNED    4
-/* Block is part of a compacted generation */
-#define BF_COMPACTED 8
+/* Block is to be marked, not copied */
+#define BF_MARKED    8
 /* Block is free, and on the free list  (TODO: is this used?) */
 #define BF_FREE      16
 /* Block is executable */
 #define BF_EXEC	     32
+/* Block contains only a small amount of live data */
+#define BF_FRAGMENTED 64
+
 
 /* Finding the block descriptor for a given block -------------------------- */
 
diff --git a/includes/RtsFlags.h b/includes/RtsFlags.h
index 7d0b418aa1..11133efe1f 100644
--- a/includes/RtsFlags.h
+++ b/includes/RtsFlags.h
@@ -39,6 +39,8 @@ struct GC_FLAGS {
     rtsBool compact;		/* True <=> "compact all the time" */
     double  compactThreshold;
 
+    rtsBool sweep;		/* use "mostly mark-sweep" instead of copying
+                                 * for the oldest generation */
     rtsBool ringBell;
     rtsBool frontpanel;
 
diff --git a/includes/Storage.h b/includes/Storage.h
index ae066c1c9e..34a5411918 100644
--- a/includes/Storage.h
+++ b/includes/Storage.h
@@ -55,7 +55,6 @@
 typedef struct step_ {
     unsigned int         no;		// step number in this generation
     unsigned int         abs_no;	// absolute step number
-    int                  is_compacted;	// compact this step? (old gen only)
 
     struct generation_ * gen;		// generation this step belongs to
     unsigned int         gen_no;        // generation number (cached)
@@ -87,8 +86,12 @@ typedef struct step_ {
                                         //    and scavenged_large_objects
 #endif
 
+    int          mark;			// mark (not copy)? (old gen only)
+    int          compact;		// compact (not sweep)? (old gen only)
+
     bdescr *     old_blocks;	        // bdescr of first from-space block
     unsigned int n_old_blocks;		// number of blocks in from-space
+    unsigned int live_estimate;         // for sweeping: estimate of live data
     
     bdescr *     todos;		        // blocks waiting to be scavenged
     bdescr *     todos_last;