Refactoring of the GC in preparation for parallel GC

[ghc-hetmet.git] / rts / sm / GCUtils.c

diff --git a/rts/sm/GCUtils.c b/rts/sm/GCUtils.c
index 61b72b6..cee17c4 100644 (file)
--- a/rts/sm/GCUtils.c
+++ b/rts/sm/GCUtils.c
@@ -12,73 +12,172 @@
  * ---------------------------------------------------------------------------*/
 
 #include "Rts.h"
+#include "RtsFlags.h"
 #include "Storage.h"
 #include "GC.h"
 #include "GCUtils.h"
+#include "Printer.h"
+
+#ifdef THREADED_RTS
+SpinLock gc_alloc_block_sync;
+#endif
+
+bdescr *
+allocBlock_sync(void)
+{
+    bdescr *bd;
+    ACQUIRE_SPIN_LOCK(&gc_alloc_block_sync);
+    bd = allocBlock();
+    RELEASE_SPIN_LOCK(&gc_alloc_block_sync);
+    return bd;
+}
 
 /* -----------------------------------------------------------------------------
-   Allocate a new to-space block in the given step.
+   Workspace utilities
    -------------------------------------------------------------------------- */
 
 bdescr *
-gc_alloc_block(step *stp)
+grab_todo_block (step_workspace *ws)
 {
-    bdescr *bd = allocBlock();
-    bd->gen_no = stp->gen_no;
-    bd->step = stp;
+    bdescr *bd;
+    step *stp;
+
+    stp = ws->stp;
+    bd = NULL;
+
+    if (ws->buffer_todo_bd)
+    {
+       bd = ws->buffer_todo_bd;
+       ASSERT(bd->link == NULL);
+       ws->buffer_todo_bd = NULL;
+       return bd;
+    }
+
+    ACQUIRE_SPIN_LOCK(&stp->sync_todo);
+    if (stp->todos) {
+       bd = stp->todos;
+       stp->todos = bd->link;
+       bd->link = NULL;
+    }  
+    RELEASE_SPIN_LOCK(&stp->sync_todo);
+    return bd;
+}
+
+static void
+push_todo_block (bdescr *bd, step *stp)
+{
+    ASSERT(bd->link == NULL);
+    ACQUIRE_SPIN_LOCK(&stp->sync_todo);
+    bd->link = stp->todos;
+    stp->todos = bd;
+    RELEASE_SPIN_LOCK(&stp->sync_todo);
+}
+
+void
+push_scan_block (bdescr *bd, step_workspace *ws)
+{
+    ASSERT(bd != NULL);
+    ASSERT(bd->link == NULL);
+
+    // update stats: this is a block that has been copied & scavenged
+    copied += bd->free - bd->start;
+
+    // put the scan block *second* in ws->scavd_list.  The first block
+    // in this list is for evacuating objects that don't need to be
+    // scavenged.
+    bd->link = ws->scavd_list->link;
+    ws->scavd_list->link = bd;
+    ws->n_scavd_blocks ++;
+
+    IF_DEBUG(sanity, 
+            ASSERT(countBlocks(ws->scavd_list) == ws->n_scavd_blocks));
+}
+
+bdescr *
+gc_alloc_todo_block (step_workspace *ws)
+{
+    bdescr *bd;
+
+    // If we already have a todo block, it must be full, so we push it
+    // out: first to the buffer_todo_bd, then to the step.  BUT, don't
+    // push out the block out if it is already the scan block.
+    if (ws->todo_bd != NULL && ws->scan_bd != ws->todo_bd) {
+       ASSERT(ws->todo_bd->link == NULL);
+       if (ws->buffer_todo_bd != NULL) {
+           ASSERT(ws->buffer_todo_bd->link == NULL);
+           push_todo_block(ws->buffer_todo_bd, ws->stp);
+       }
+       ws->buffer_todo_bd = ws->todo_bd;
+       ws->todo_bd = NULL;
+    }      
+
+    bd = allocBlock_sync();
+
+    bd->gen_no = ws->stp->gen_no;
+    bd->step = ws->stp;
     bd->link = NULL;
 
     // blocks in to-space in generations up to and including N
     // get the BF_EVACUATED flag.
-    if (stp->gen_no <= N) {
+    if (ws->stp->gen_no <= N) {
        bd->flags = BF_EVACUATED;
     } else {
        bd->flags = 0;
     }
-
-    // Start a new to-space block, chain it on after the previous one.
-    if (stp->hp_bd != NULL) {
-       stp->hp_bd->free = stp->hp;
-       stp->hp_bd->link = bd;
-    }
-
-    stp->hp_bd = bd;
-    stp->hp    = bd->start;
-    stp->hpLim = stp->hp + BLOCK_SIZE_W;
-
-    stp->n_blocks++;
-    new_blocks++;
+       
+    ws->todo_bd = bd;
 
     return bd;
 }
 
 bdescr *
-gc_alloc_scavd_block(step *stp)
+gc_alloc_scavd_block (step_workspace *ws)
 {
-    bdescr *bd = allocBlock();
-    bd->gen_no = stp->gen_no;
-    bd->step = stp;
+    bdescr *bd;
+
+    bd = allocBlock_sync();
+
+    bd->gen_no = ws->stp->gen_no;
+    bd->step = ws->stp;
 
     // blocks in to-space in generations up to and including N
     // get the BF_EVACUATED flag.
-    if (stp->gen_no <= N) {
+    if (ws->stp->gen_no <= N) {
        bd->flags = BF_EVACUATED;
     } else {
        bd->flags = 0;
     }
 
-    bd->link = stp->blocks;
-    stp->blocks = bd;
-
-    if (stp->scavd_hp != NULL) {
-       Bdescr(stp->scavd_hp)->free = stp->scavd_hp;
+    // update stats: this is a block that has been copied only
+    if (ws->scavd_list != NULL) {
+       scavd_copied += ws->scavd_list->free - ws->scavd_list->start;
     }
-    stp->scavd_hp    = bd->start;
-    stp->scavd_hpLim = stp->scavd_hp + BLOCK_SIZE_W;
 
-    stp->n_blocks++;
-    new_scavd_blocks++;
+    bd->link = ws->scavd_list;
+    ws->scavd_list = bd;
+    ws->n_scavd_blocks++;
 
     return bd;
 }
 
+/* -----------------------------------------------------------------------------
+ * Debugging
+ * -------------------------------------------------------------------------- */
+
+#if DEBUG
+void
+printMutableList(generation *gen)
+{
+    bdescr *bd;
+    StgPtr p;
+
+    debugBelch("mutable list %p: ", gen->mut_list);
+
+    for (bd = gen->mut_list; bd != NULL; bd = bd->link) {
+       for (p = bd->start; p < bd->free; p++) {
+           debugBelch("%p (%s), ", (void *)*p, info_type((StgClosure *)*p));
+       }
+    }
+    debugBelch("\n");
+}
+#endif /* DEBUG */