First version of GC counting objects for control

Still needs to review generational mode.

lapi.c

@@ -1154,11 +1154,11 @@ LUA_API int lua_gc (lua_State *L, int what, ...) {
     }
     case LUA_GCCOUNT: {
       /* GC values are expressed in Kbytes: #bytes/2^10 */
-      res = cast_int(gettotalbytes(g) >> 10);
+      res = cast_int(g->totalbytes >> 10);
       break;
     }
     case LUA_GCCOUNTB: {
-      res = cast_int(gettotalbytes(g) & 0x3ff);
+      res = cast_int(g->totalbytes & 0x3ff);
       break;
     }
     case LUA_GCSTEP: {
@@ -1171,7 +1171,7 @@ LUA_API int lua_gc (lua_State *L, int what, ...) {
         luaC_step(L);
       }
       else {  /* add 'data' to total debt */
-        debt = cast(l_mem, data) * 1024 + g->GCdebt;
+        debt = data + g->GCdebt;
         luaE_setdebt(g, debt);
         luaC_checkGC(L);
       }
@@ -1217,7 +1217,8 @@ LUA_API int lua_gc (lua_State *L, int what, ...) {
       if (stepmul != 0)
         setgcparam(g->gcstepmul, stepmul);
       if (stepsize != 0)
-        g->gcstepsize = stepsize;
+        g->gcstepsize = (stepsize <= log2maxs(l_mem)) ? stepsize
+                                                      : log2maxs(l_mem);
       luaC_changemode(L, KGC_INC);
       break;
     }

lgc.c

@@ -19,6 +19,7 @@
 #include "ldo.h"
 #include "lfunc.h"
 #include "lgc.h"
+#include "llex.h"
 #include "lmem.h"
 #include "lobject.h"
 #include "lstate.h"
@@ -32,7 +33,7 @@
 ** (Large enough to dissipate fixed overheads but small enough
 ** to allow small steps for the collector.)
 */
-#define GCSWEEPMAX	100
+#define GCSWEEPMAX	20
 
 /*
 ** Maximum number of finalizers to call in each single step.
@@ -46,19 +47,6 @@
 #define GCFINALIZECOST	50
 
 
-/*
-** The equivalent, in bytes, of one unit of "work" (visiting a slot,
-** sweeping an object, etc.)
-*/
-#define WORK2MEM	sizeof(TValue)
-
-
-/*
-** macro to adjust 'pause': 'pause' is actually used like
-** 'pause / PAUSEADJ' (value chosen by tests)
-*/
-#define PAUSEADJ		100
-
 
 /* mask with all color bits */
 #define maskcolors	(bitmask(BLACKBIT) | WHITEBITS)
@@ -105,7 +93,7 @@
 #define markobjectN(g,t)	{ if (t) markobject(g,t); }
 
 static void reallymarkobject (global_State *g, GCObject *o);
-static lu_mem atomic (lua_State *L);
+static l_mem atomic (lua_State *L);
 static void entersweep (lua_State *L);
 
 
@@ -259,7 +247,7 @@ GCObject *luaC_newobjdt (lua_State *L, int tt, size_t sz, size_t offset) {
   global_State *g = G(L);
   char *p = cast_charp(luaM_newobject(L, novariant(tt), sz));
   GCObject *o = cast(GCObject *, p + offset);
-  g->totalobjs++;
+  g->GCdebt++;
   o->marked = luaC_white(g);
   o->tt = tt;
   o->next = g->allgc;
@@ -268,6 +256,9 @@ GCObject *luaC_newobjdt (lua_State *L, int tt, size_t sz, size_t offset) {
 }
 
 
+/*
+** create a new collectable object with no offset.
+*/
 GCObject *luaC_newobj (lua_State *L, int tt, size_t sz) {
   return luaC_newobjdt(L, tt, sz, 0);
 }
@@ -296,6 +287,7 @@ GCObject *luaC_newobj (lua_State *L, int tt, size_t sz) {
 ** (only closures can), and a userdata's metatable must be a table.
 */
 static void reallymarkobject (global_State *g, GCObject *o) {
+  g->marked++;
   switch (o->tt) {
     case LUA_VSHRSTR:
     case LUA_VLNGSTR: {
@@ -343,9 +335,9 @@ static void markmt (global_State *g) {
 /*
 ** mark all objects in list of being-finalized
 */
-static lu_mem markbeingfnz (global_State *g) {
+static l_mem markbeingfnz (global_State *g) {
   GCObject *o;
-  lu_mem count = 0;
+  l_mem count = 0;
   for (o = g->tobefnz; o != NULL; o = o->next) {
     count++;
     markobject(g, o);
@@ -365,12 +357,11 @@ static lu_mem markbeingfnz (global_State *g) {
 ** upvalues, as they have nothing to be checked. (If the thread gets an
 ** upvalue later, it will be linked in the list again.)
 */
-static int remarkupvals (global_State *g) {
+static l_mem remarkupvals (global_State *g) {
+  l_mem work = 0;
   lua_State *thread;
   lua_State **p = &g->twups;
-  int work = 0;  /* estimate of how much work was done here */
   while ((thread = *p) != NULL) {
-    work++;
     if (!iswhite(thread) && thread->openupval != NULL)
       p = &thread->twups;  /* keep marked thread with upvalues in the list */
     else {  /* thread is not marked or without upvalues */
@@ -380,13 +371,13 @@ static int remarkupvals (global_State *g) {
       thread->twups = thread;  /* mark that it is out of list */
       for (uv = thread->openupval; uv != NULL; uv = uv->u.open.next) {
         lua_assert(getage(uv) <= getage(thread));
-        work++;
         if (!iswhite(uv)) {  /* upvalue already visited? */
           lua_assert(upisopen(uv) && isgray(uv));
           markvalue(g, uv->v.p);  /* mark its value */
         }
       }
     }
+    work++;
   }
   return work;
 }
@@ -399,10 +390,15 @@ static void cleargraylists (global_State *g) {
 
 
 /*
-** mark root set and reset all gray lists, to start a new collection
+** mark root set and reset all gray lists, to start a new collection.
+** 'marked' is initialized with the number of fixed objects in the state,
+** to count the total number of live objects during a cycle. (That is
+** the metafield names, plus the reserved words, plus "_ENV" plus the
+** memory-error message.)
 */
 static void restartcollection (global_State *g) {
   cleargraylists(g);
+  g->marked = TM_N + NUM_RESERVED + 2;
   markobject(g, g->mainthread);
   markvalue(g, &g->l_registry);
   markmt(g);
@@ -540,7 +536,7 @@ static void traversestrongtable (global_State *g, Table *h) {
 }
 
 
-static lu_mem traversetable (global_State *g, Table *h) {
+static void traversetable (global_State *g, Table *h) {
   const char *weakkey, *weakvalue;
   const TValue *mode = gfasttm(g, h->metatable, TM_MODE);
   markobjectN(g, h->metatable);
@@ -557,17 +553,15 @@ static lu_mem traversetable (global_State *g, Table *h) {
   }
   else  /* not weak */
     traversestrongtable(g, h);
-  return 1 + h->alimit + 2 * allocsizenode(h);
 }
 
 
-static int traverseudata (global_State *g, Udata *u) {
+static void traverseudata (global_State *g, Udata *u) {
   int i;
   markobjectN(g, u->metatable);  /* mark its metatable */
   for (i = 0; i < u->nuvalue; i++)
     markvalue(g, &u->uv[i].uv);
   genlink(g, obj2gco(u));
-  return 1 + u->nuvalue;
 }
 
 
@@ -576,7 +570,7 @@ static int traverseudata (global_State *g, Udata *u) {
 ** arrays can be larger than needed; the extra slots are filled with
 ** NULL, so the use of 'markobjectN')
 */
-static int traverseproto (global_State *g, Proto *f) {
+static void traverseproto (global_State *g, Proto *f) {
   int i;
   markobjectN(g, f->source);
   for (i = 0; i < f->sizek; i++)  /* mark literals */
@@ -587,29 +581,26 @@ static int traverseproto (global_State *g, Proto *f) {
     markobjectN(g, f->p[i]);
   for (i = 0; i < f->sizelocvars; i++)  /* mark local-variable names */
     markobjectN(g, f->locvars[i].varname);
-  return 1 + f->sizek + f->sizeupvalues + f->sizep + f->sizelocvars;
 }
 
 
-static int traverseCclosure (global_State *g, CClosure *cl) {
+static void traverseCclosure (global_State *g, CClosure *cl) {
   int i;
   for (i = 0; i < cl->nupvalues; i++)  /* mark its upvalues */
     markvalue(g, &cl->upvalue[i]);
-  return 1 + cl->nupvalues;
 }
 
 /*
 ** Traverse a Lua closure, marking its prototype and its upvalues.
 ** (Both can be NULL while closure is being created.)
 */
-static int traverseLclosure (global_State *g, LClosure *cl) {
+static void traverseLclosure (global_State *g, LClosure *cl) {
   int i;
   markobjectN(g, cl->p);  /* mark its prototype */
   for (i = 0; i < cl->nupvalues; i++) {  /* visit its upvalues */
     UpVal *uv = cl->upvals[i];
     markobjectN(g, uv);  /* mark upvalue */
   }
-  return 1 + cl->nupvalues;
 }
 
 
@@ -625,13 +616,13 @@ static int traverseLclosure (global_State *g, LClosure *cl) {
 ** (which can only happen in generational mode) or if the traverse is in
 ** the propagate phase (which can only happen in incremental mode).
 */
-static int traversethread (global_State *g, lua_State *th) {
+static void traversethread (global_State *g, lua_State *th) {
   UpVal *uv;
   StkId o = th->stack.p;
   if (isold(th) || g->gcstate == GCSpropagate)
     linkgclist(th, g->grayagain);  /* insert into 'grayagain' list */
   if (o == NULL)
-    return 1;  /* stack not completely built yet */
+    return;  /* stack not completely built yet */
   lua_assert(g->gcstate == GCSatomic ||
              th->openupval == NULL || isintwups(th));
   for (; o < th->top.p; o++)  /* mark live elements in the stack */
@@ -649,34 +640,35 @@ static int traversethread (global_State *g, lua_State *th) {
   }
   else if (!g->gcemergency)
     luaD_shrinkstack(th); /* do not change stack in emergency cycle */
-  return 1 + stacksize(th);
 }
 
 
 /*
 ** traverse one gray object, turning it to black.
 */
-static lu_mem propagatemark (global_State *g) {
+static void propagatemark (global_State *g) {
   GCObject *o = g->gray;
   nw2black(o);
   g->gray = *getgclist(o);  /* remove from 'gray' list */
   switch (o->tt) {
-    case LUA_VTABLE: return traversetable(g, gco2t(o));
-    case LUA_VUSERDATA: return traverseudata(g, gco2u(o));
-    case LUA_VLCL: return traverseLclosure(g, gco2lcl(o));
-    case LUA_VCCL: return traverseCclosure(g, gco2ccl(o));
-    case LUA_VPROTO: return traverseproto(g, gco2p(o));
-    case LUA_VTHREAD: return traversethread(g, gco2th(o));
-    default: lua_assert(0); return 0;
+    case LUA_VTABLE: traversetable(g, gco2t(o)); break;
+    case LUA_VUSERDATA: traverseudata(g, gco2u(o)); break;
+    case LUA_VLCL: traverseLclosure(g, gco2lcl(o)); break;
+    case LUA_VCCL: traverseCclosure(g, gco2ccl(o)); break;
+    case LUA_VPROTO: traverseproto(g, gco2p(o)); break;
+    case LUA_VTHREAD: traversethread(g, gco2th(o)); break;
+    default: lua_assert(0);
   }
 }
 
 
-static lu_mem propagateall (global_State *g) {
-  lu_mem tot = 0;
-  while (g->gray)
-    tot += propagatemark(g);
-  return tot;
+static l_mem propagateall (global_State *g) {
+  l_mem work = 0;
+  while (g->gray) {
+    propagatemark(g);
+    work++;
+  }
+  return work;
 }
 
 
@@ -685,10 +677,10 @@ static lu_mem propagateall (global_State *g) {
 ** Repeat until it converges, that is, nothing new is marked. 'dir'
 ** inverts the direction of the traversals, trying to speed up
 ** convergence on chains in the same table.
-**
 */
-static void convergeephemerons (global_State *g) {
+static l_mem convergeephemerons (global_State *g) {
   int changed;
+  l_mem work = 0;
   int dir = 0;
   do {
     GCObject *w;
@@ -703,9 +695,11 @@ static void convergeephemerons (global_State *g) {
         propagateall(g);  /* propagate changes */
         changed = 1;  /* will have to revisit all ephemeron tables */
       }
+      work++;
     }
     dir = !dir;  /* invert direction next time */
   } while (changed);  /* repeat until no more changes */
+  return work;
 }
 
 /* }====================================================== */
@@ -721,7 +715,8 @@ static void convergeephemerons (global_State *g) {
 /*
 ** clear entries with unmarked keys from all weaktables in list 'l'
 */
-static void clearbykeys (global_State *g, GCObject *l) {
+static l_mem clearbykeys (global_State *g, GCObject *l) {
+  l_mem work = 0;
   for (; l; l = gco2t(l)->gclist) {
     Table *h = gco2t(l);
     Node *limit = gnodelast(h);
@@ -732,7 +727,9 @@ static void clearbykeys (global_State *g, GCObject *l) {
       if (isempty(gval(n)))  /* is entry empty? */
         clearkey(n);  /* clear its key */
     }
+    work++;
   }
+  return work;
 }
 
 
@@ -740,7 +737,8 @@ static void clearbykeys (global_State *g, GCObject *l) {
 ** clear entries with unmarked values from all weaktables in list 'l' up
 ** to element 'f'
 */
-static void clearbyvalues (global_State *g, GCObject *l, GCObject *f) {
+static l_mem clearbyvalues (global_State *g, GCObject *l, GCObject *f) {
+  l_mem work = 0;
   for (; l != f; l = gco2t(l)->gclist) {
     Table *h = gco2t(l);
     Node *n, *limit = gnodelast(h);
@@ -757,7 +755,9 @@ static void clearbyvalues (global_State *g, GCObject *l, GCObject *f) {
       if (isempty(gval(n)))  /* is entry empty? */
         clearkey(n);  /* clear its key */
     }
+    work++;
   }
+  return work;
 }
 
 
@@ -819,10 +819,9 @@ static void freeobj (lua_State *L, GCObject *o) {
 ** objects, where a dead object is one marked with the old (non current)
 ** white; change all non-dead objects back to white, preparing for next
 ** collection cycle. Return where to continue the traversal or NULL if
-** list is finished. ('*countout' gets the number of elements traversed.)
+** list is finished.
 */
-static GCObject **sweeplist (lua_State *L, GCObject **p, int countin,
-                             int *countout) {
+static GCObject **sweeplist (lua_State *L, GCObject **p, int countin) {
   global_State *g = G(L);
   int ow = otherwhite(g);
   int i;
@@ -839,8 +838,6 @@ static GCObject **sweeplist (lua_State *L, GCObject **p, int countin,
       p = &curr->next;  /* go to next element */
     }
   }
-  if (countout)
-    *countout = i;  /* number of elements traversed */
   return (*p == NULL) ? NULL : p;
 }
 
@@ -851,7 +848,7 @@ static GCObject **sweeplist (lua_State *L, GCObject **p, int countin,
 static GCObject **sweeptolive (lua_State *L, GCObject **p) {
   GCObject **old = p;
   do {
-    p = sweeplist(L, p, 1, NULL);
+    p = sweeplist(L, p, 1);
   } while (p == old);
   return p;
 }
@@ -870,11 +867,8 @@ static GCObject **sweeptolive (lua_State *L, GCObject **p) {
 */
 static void checkSizes (lua_State *L, global_State *g) {
   if (!g->gcemergency) {
-    if (g->strt.nuse < g->strt.size / 4) {  /* string table too big? */
-      l_mem olddebt = g->GCdebt;
+    if (g->strt.nuse < g->strt.size / 4)  /* string table too big? */
       luaS_resize(L, g->strt.size / 2);
-      g->GCestimate += g->GCdebt - olddebt;  /* correct estimate */
-    }
   }
 }
 
@@ -935,12 +929,11 @@ static void GCTM (lua_State *L) {
 /*
 ** Call a few finalizers
 */
-static int runafewfinalizers (lua_State *L, int n) {
+static void runafewfinalizers (lua_State *L, int n) {
   global_State *g = G(L);
   int i;
   for (i = 0; i < n && g->tobefnz; i++)
     GCTM(L);  /* call one finalizer */
-  return i;
 }
 
 
@@ -1052,19 +1045,16 @@ void luaC_checkfinalizer (lua_State *L, GCObject *o, Table *mt) {
 
 /*
 ** Set the "time" to wait before starting a new GC cycle; cycle will
-** start when memory use hits the threshold of ('estimate' * pause /
-** PAUSEADJ). (Division by 'estimate' should be OK: it cannot be zero,
-** because Lua cannot even start with less than PAUSEADJ bytes).
+** start when number of objects in use hits the threshold of
+** approximately ('marked' * pause / 100). (A direct multiplication
+** by 'pause' may overflow, and a direct division by 100 may undeflow
+** to zero. So, the division is done in two steps. 8 * 12 is near 100
+** and the division by 8 is cheap.)
 */
 static void setpause (global_State *g) {
-  l_mem threshold, debt;
-  int pause = getgcparam(g->gcpause);
-  l_mem estimate = g->GCestimate / PAUSEADJ;  /* adjust 'estimate' */
-  lua_assert(estimate > 0);
-  threshold = (pause < MAX_LMEM / estimate)  /* overflow? */
-            ? estimate * pause  /* no overflow */
-            : MAX_LMEM;  /* overflow; truncate to maximum */
-  debt = gettotalbytes(g) - threshold;
+  unsigned int pause = getgcparam(g->gcpause);
+  lu_mem threshold = g->marked / 8 * pause / 12;
+  l_mem debt = gettotalobjs(g) - threshold;
   if (debt > 0) debt = 0;
   luaE_setdebt(g, debt);
 }
@@ -1306,17 +1296,17 @@ static void atomic2gen (lua_State *L, global_State *g) {
 
   g->gckind = KGC_GEN;
   g->lastatomic = 0;
-  g->GCestimate = gettotalbytes(g);  /* base for memory control */
+  g->GCestimate = gettotalobjs(g);  /* base for memory control */
   finishgencycle(L, g);
 }
 
 
 /*
 ** Set debt for the next minor collection, which will happen when
-** memory grows 'genminormul'%.
+** total number of objects grows 'genminormul'%.
 */
 static void setminordebt (global_State *g) {
-  luaE_setdebt(g, -(cast(l_mem, (gettotalbytes(g) / 100)) * g->genminormul));
+  luaE_setdebt(g, -(cast(l_mem, (gettotalobjs(g) / 100)) * g->genminormul));
 }
 
 
@@ -1326,14 +1316,12 @@ static void setminordebt (global_State *g) {
 ** are cleared. Then, turn all objects into old and finishes the
 ** collection.
 */
-static lu_mem entergen (lua_State *L, global_State *g) {
-  lu_mem numobjs;
+static void entergen (lua_State *L, global_State *g) {
   luaC_runtilstate(L, bitmask(GCSpause));  /* prepare to start a new cycle */
   luaC_runtilstate(L, bitmask(GCSpropagate));  /* start new cycle */
-  numobjs = atomic(L);  /* propagates all and then do the atomic stuff */
+  atomic(L);  /* propagates all and then do the atomic stuff */
   atomic2gen(L, g);
   setminordebt(g);  /* set debt assuming next cycle will be minor */
-  return numobjs;
 }
 
 
@@ -1372,9 +1360,9 @@ void luaC_changemode (lua_State *L, int newmode) {
 /*
 ** Does a full collection in generational mode.
 */
-static lu_mem fullgen (lua_State *L, global_State *g) {
+static void fullgen (lua_State *L, global_State *g) {
   enterinc(g);
-  return entergen(L, g);
+  entergen(L, g);
 }
 
 
@@ -1400,22 +1388,22 @@ static lu_mem fullgen (lua_State *L, global_State *g) {
 ** ('g->lastatomic != 0' also means that the last collection was bad.)
 */
 static void stepgenfull (lua_State *L, global_State *g) {
-  lu_mem newatomic;  /* count of traversed objects */
   lu_mem lastatomic = g->lastatomic;  /* count from last collection */
   if (g->gckind == KGC_GEN)  /* still in generational mode? */
     enterinc(g);  /* enter incremental mode */
   luaC_runtilstate(L, bitmask(GCSpropagate));  /* start new cycle */
-  newatomic = atomic(L);  /* mark everybody */
-  if (newatomic < lastatomic + (lastatomic >> 3)) {  /* good collection? */
+  g->marked = 0;
+  atomic(L);  /* mark everybody */
+  if (g->marked < lastatomic + (lastatomic >> 3)) {  /* good collection? */
     atomic2gen(L, g);  /* return to generational mode */
     setminordebt(g);
   }
   else {  /* another bad collection; stay in incremental mode */
-    g->GCestimate = gettotalbytes(g);  /* first estimate */;
+    g->GCestimate = gettotalobjs(g);  /* first estimate */;
+    g->lastatomic = g->marked;
     entersweep(L);
     luaC_runtilstate(L, bitmask(GCSpause));  /* finish collection */
     setpause(g);
-    g->lastatomic = newatomic;
   }
 }
 
@@ -1443,21 +1431,23 @@ static void genstep (lua_State *L, global_State *g) {
   if (g->lastatomic != 0)  /* last collection was a bad one? */
     stepgenfull(L, g);  /* do a full step */
   else {
-    lu_mem majorbase = g->GCestimate;  /* memory after last major collection */
-    lu_mem majorinc = (majorbase / 100) * getgcparam(g->genmajormul);
-    if (g->GCdebt > 0 && gettotalbytes(g) > majorbase + majorinc) {
-      lu_mem numobjs = fullgen(L, g);  /* do a major collection */
-      if (gettotalbytes(g) < majorbase + (majorinc / 2)) {
-        /* collected at least half of memory growth since last major
+    l_mem majorbase = g->GCestimate;  /* objects after last major collection */
+    l_mem majorinc = (majorbase / 100) * getgcparam(g->genmajormul);
+    if (g->GCdebt > 0 && gettotalobjs(g) > majorbase + majorinc) {
+      g->marked = 0;
+      fullgen(L, g);  /* do a major collection */
+      if (gettotalobjs(g) < majorbase + (majorinc / 2)) {
+        /* collected at least half of object growth since last major
            collection; keep doing minor collections. */
         lua_assert(g->lastatomic == 0);
       }
       else {  /* bad collection */
-        g->lastatomic = numobjs;  /* signal that last collection was bad */
+        g->lastatomic = g->marked;  /* signal that last collection was bad */
         setpause(g);  /* do a long wait for next (major) collection */
       }
     }
     else {  /* regular case; do a minor collection */
+      g->marked = 0;
       youngcollection(L, g);
       setminordebt(g);
       g->GCestimate = majorbase;  /* preserve base value */
@@ -1522,9 +1512,9 @@ void luaC_freeallobjects (lua_State *L) {
 }
 
 
-static lu_mem atomic (lua_State *L) {
+static l_mem atomic (lua_State *L) {
+  l_mem work = 0;
   global_State *g = G(L);
-  lu_mem work = 0;
   GCObject *origweak, *origall;
   GCObject *grayagain = g->grayagain;  /* save original list */
   g->grayagain = NULL;
@@ -1541,50 +1531,47 @@ static lu_mem atomic (lua_State *L) {
   work += propagateall(g);  /* propagate changes */
   g->gray = grayagain;
   work += propagateall(g);  /* traverse 'grayagain' list */
-  convergeephemerons(g);
+  work += convergeephemerons(g);
   /* at this point, all strongly accessible objects are marked. */
   /* Clear values from weak tables, before checking finalizers */
-  clearbyvalues(g, g->weak, NULL);
-  clearbyvalues(g, g->allweak, NULL);
+  work += clearbyvalues(g, g->weak, NULL);
+  work += clearbyvalues(g, g->allweak, NULL);
   origweak = g->weak; origall = g->allweak;
   separatetobefnz(g, 0);  /* separate objects to be finalized */
   work += markbeingfnz(g);  /* mark objects that will be finalized */
   work += propagateall(g);  /* remark, to propagate 'resurrection' */
-  convergeephemerons(g);
+  work += convergeephemerons(g);
   /* at this point, all resurrected objects are marked. */
   /* remove dead objects from weak tables */
-  clearbykeys(g, g->ephemeron);  /* clear keys from all ephemeron tables */
-  clearbykeys(g, g->allweak);  /* clear keys from all 'allweak' tables */
+  work += clearbykeys(g, g->ephemeron);  /* clear keys from all ephemeron */
+  work += clearbykeys(g, g->allweak);  /* clear keys from all 'allweak' */
   /* clear values from resurrected weak tables */
-  clearbyvalues(g, g->weak, origweak);
-  clearbyvalues(g, g->allweak, origall);
+  work += clearbyvalues(g, g->weak, origweak);
+  work += clearbyvalues(g, g->allweak, origall);
   luaS_clearcache(g);
   g->currentwhite = cast_byte(otherwhite(g));  /* flip current white */
   lua_assert(g->gray == NULL);
-  return work;  /* estimate of slots marked by 'atomic' */
+  return work;
 }
 
 
-static int sweepstep (lua_State *L, global_State *g,
-                      int nextstate, GCObject **nextlist) {
+static void sweepstep (lua_State *L, global_State *g,
+                       int nextstate, GCObject **nextlist) {
   if (g->sweepgc) {
     l_mem olddebt = g->GCdebt;
-    int count;
-    g->sweepgc = sweeplist(L, g->sweepgc, GCSWEEPMAX, &count);
+    g->sweepgc = sweeplist(L, g->sweepgc, GCSWEEPMAX);
     g->GCestimate += g->GCdebt - olddebt;  /* update estimate */
-    return count;
   }
   else {  /* enter next state */
     g->gcstate = nextstate;
     g->sweepgc = nextlist;
-    return 0;  /* no work done */
   }
 }
 
 
-static lu_mem singlestep (lua_State *L) {
+static l_mem singlestep (lua_State *L) {
   global_State *g = G(L);
-  lu_mem work;
+  l_mem work;
   lua_assert(!g->gcstopem);  /* collector is not reentrant */
   g->gcstopem = 1;  /* no emergency collections while collecting */
   switch (g->gcstate) {
@@ -1599,26 +1586,30 @@ static lu_mem singlestep (lua_State *L) {
         g->gcstate = GCSenteratomic;  /* finish propagate phase */
         work = 0;
       }
-      else
-        work = propagatemark(g);  /* traverse one gray object */
+      else {
+        propagatemark(g);  /* traverse one gray object */
+        work = 1;
+      }
       break;
     }
     case GCSenteratomic: {
-      work = atomic(L);  /* work is what was traversed by 'atomic' */
+      work = atomic(L);
       entersweep(L);
-      g->GCestimate = gettotalbytes(g);  /* first estimate */;
       break;
     }
     case GCSswpallgc: {  /* sweep "regular" objects */
-      work = sweepstep(L, g, GCSswpfinobj, &g->finobj);
+      sweepstep(L, g, GCSswpfinobj, &g->finobj);
+      work = GCSWEEPMAX;
       break;
     }
     case GCSswpfinobj: {  /* sweep objects with finalizers */
-      work = sweepstep(L, g, GCSswptobefnz, &g->tobefnz);
+      sweepstep(L, g, GCSswptobefnz, &g->tobefnz);
+      work = GCSWEEPMAX;
       break;
     }
     case GCSswptobefnz: {  /* sweep objects to be finalized */
-      work = sweepstep(L, g, GCSswpend, NULL);
+      sweepstep(L, g, GCSswpend, NULL);
+      work = GCSWEEPMAX;
       break;
     }
     case GCSswpend: {  /* finish sweeps */
@@ -1630,7 +1621,8 @@ static lu_mem singlestep (lua_State *L) {
     case GCScallfin: {  /* call remaining finalizers */
       if (g->tobefnz && !g->gcemergency) {
         g->gcstopem = 0;  /* ok collections during finalizers */
-        work = runafewfinalizers(L, GCFINMAX) * GCFINALIZECOST;
+        runafewfinalizers(L, GCFINMAX);
+        work = GCFINMAX * GCFINALIZECOST;
       }
       else {  /* emergency mode or no more finalizers */
         g->gcstate = GCSpause;  /* finish collection */
@@ -1666,18 +1658,16 @@ void luaC_runtilstate (lua_State *L, int statesmask) {
 */
 static void incstep (lua_State *L, global_State *g) {
   int stepmul = (getgcparam(g->gcstepmul) | 1);  /* avoid division by 0 */
-  l_mem debt = (g->GCdebt / WORK2MEM) * stepmul;
-  l_mem stepsize = (g->gcstepsize <= log2maxs(l_mem))
-                 ? ((cast(l_mem, 1) << g->gcstepsize) / WORK2MEM) * stepmul
-                 : MAX_LMEM;  /* overflow; keep maximum value */
+  l_mem debt = (g->GCdebt / 100) * stepmul;
+  l_mem stepsize = cast(l_mem, 1) << g->gcstepsize;
   do {  /* repeat until pause or enough "credit" (negative debt) */
-    lu_mem work = singlestep(L);  /* perform one single step */
+    l_mem work = singlestep(L);  /* perform one single step */
     debt -= work;
   } while (debt > -stepsize && g->gcstate != GCSpause);
   if (g->gcstate == GCSpause)
     setpause(g);  /* pause until next cycle */
   else {
-    debt = (debt / stepmul) * WORK2MEM;  /* convert 'work units' to bytes */
+    debt = (debt / stepmul) * 100;  /* apply step multiplier */
     luaE_setdebt(g, debt);
   }
 }
@@ -1710,9 +1700,8 @@ static void fullinc (lua_State *L, global_State *g) {
   /* finish any pending sweep phase to start a new cycle */
   luaC_runtilstate(L, bitmask(GCSpause));
   luaC_runtilstate(L, bitmask(GCScallfin));  /* run up to finalizers */
-  /* estimate must be correct after a full GC cycle */
-  lua_assert(g->GCestimate == gettotalbytes(g));
   luaC_runtilstate(L, bitmask(GCSpause));  /* finish collection */
+  /* estimate must be correct after a full GC cycle */
   setpause(g);
 }
 

lgc.h

@@ -135,10 +135,10 @@
 #define getgcparam(p)	((p) * 4)
 #define setgcparam(p,v)	((p) = (v) / 4)
 
-#define LUAI_GCMUL      100
+#define LUAI_GCMUL      300
 
-/* how much to allocate before next GC step (log2) */
-#define LUAI_GCSTEPSIZE 13      /* 8 KB */
+/* how many objects to allocate before next GC step (log2) */
+#define LUAI_GCSTEPSIZE 8      /* 256 objects */
 
 
 /*

llimits.h

@@ -57,7 +57,7 @@ typedef signed char ls_byte;
 ** floor of the log2 of the maximum signed value for integral type 't'.
 ** (That is, maximum 'n' such that '2^n' fits in the given signed type.)
 */
-#define log2maxs(t)	(sizeof(t) * 8 - 2)
+#define log2maxs(t)	cast_int(sizeof(t) * 8 - 2)
 
 
 /*

lmem.c

@@ -133,7 +133,7 @@ void luaM_free_ (lua_State *L, void *block, size_t osize) {
   global_State *g = G(L);
   lua_assert((osize == 0) == (block == NULL));
   (*g->frealloc)(g->ud, block, osize, 0);
-  g->GCdebt -= osize;
+  g->totalbytes -= osize;
 }
 
 
@@ -167,10 +167,10 @@ void *luaM_realloc_ (lua_State *L, void *block, size_t osize, size_t nsize) {
   if (l_unlikely(newblock == NULL && nsize > 0)) {
     newblock = tryagain(L, block, osize, nsize);
     if (newblock == NULL)  /* still no memory? */
-      return NULL;  /* do not update 'GCdebt' */
+      return NULL;  /* do not update 'totalbytes' */
   }
   lua_assert((nsize == 0) == (newblock == NULL));
-  g->GCdebt = (g->GCdebt + nsize) - osize;
+  g->totalbytes += nsize - osize;
   return newblock;
 }
 
@@ -195,7 +195,7 @@ void *luaM_malloc_ (lua_State *L, size_t size, int tag) {
       if (newblock == NULL)
         luaM_error(L);
     }
-    g->GCdebt += size;
+    g->totalbytes += size;
     return newblock;
   }
 }

lstate.c

@@ -83,15 +83,15 @@ static unsigned int luai_makeseed (lua_State *L) {
 
 
 /*
-** set GCdebt to a new value keeping the value (totalbytes + GCdebt)
-** invariant (and avoiding underflows in 'totalbytes')
+** set GCdebt to a new value keeping the value (totalobjs + GCdebt)
+** invariant (and avoiding underflows in 'totalobjs')
 */
 void luaE_setdebt (global_State *g, l_mem debt) {
-  l_mem tb = gettotalbytes(g);
+  l_mem tb = gettotalobjs(g);
   lua_assert(tb > 0);
   if (debt < tb - MAX_LMEM)
-    debt = tb - MAX_LMEM;  /* will make 'totalbytes == MAX_LMEM' */
-  g->totalbytes = tb - debt;
+    debt = tb - MAX_LMEM;  /* will make 'totalobjs == MAX_LMEM' */
+  g->totalobjs = tb - debt;
   g->GCdebt = debt;
 }
 
@@ -278,8 +278,8 @@ static void close_state (lua_State *L) {
   }
   luaM_freearray(L, G(L)->strt.hash, G(L)->strt.size);
   freestack(L);
-  lua_assert(gettotalbytes(g) == sizeof(LG));
-  lua_assert(g->totalobjs == 1);
+  lua_assert(g->totalbytes == sizeof(LG));
+  lua_assert(gettotalobjs(g) == 1);
   (*g->frealloc)(g->ud, fromstate(L), sizeof(LG), 0);  /* free main block */
 }
 
@@ -389,6 +389,7 @@ LUA_API lua_State *lua_newstate (lua_Alloc f, void *ud) {
   g->twups = NULL;
   g->totalbytes = sizeof(LG);
   g->totalobjs = 1;
+  g->marked = 0;
   g->GCdebt = 0;
   g->lastatomic = 0;
   setivalue(&g->nilvalue, 0);  /* to signal that state is not yet built */

lstate.h

@@ -249,9 +249,10 @@ typedef struct CallInfo {
 typedef struct global_State {
   lua_Alloc frealloc;  /* function to reallocate memory */
   void *ud;         /* auxiliary data to 'frealloc' */
-  l_mem totalbytes;  /* number of bytes currently allocated - GCdebt */
-  l_mem totalobjs;  /* total number of objects allocated */
+  l_mem totalbytes;  /* number of bytes currently allocated */
+  l_mem totalobjs;  /* total number of objects allocated - GCdebt */
   l_mem GCdebt;  /* bytes allocated not yet compensated by the collector */
+  lu_mem marked;  /* number of objects marked in a GC cycle */
   lu_mem GCestimate;  /* an estimate of the non-garbage memory in use */
   lu_mem lastatomic;  /* see function 'genstep' in file 'lgc.c' */
   stringtable strt;  /* hash table for strings */
@@ -386,8 +387,9 @@ union GCUnion {
 #define obj2gco(v)	check_exp((v)->tt >= LUA_TSTRING, &(cast_u(v)->gc))
 
 
-/* actual number of total bytes allocated */
-#define gettotalbytes(g)	cast(lu_mem, (g)->totalbytes + (g)->GCdebt)
+/* actual number of total objects allocated */
+#define gettotalobjs(g)	((g)->totalobjs + (g)->GCdebt)
+
 
 LUAI_FUNC void luaE_setdebt (global_State *g, l_mem debt);
 LUAI_FUNC void luaE_freethread (lua_State *L, lua_State *L1);

ltests.c

@@ -1027,6 +1027,16 @@ static int table_query (lua_State *L) {
 }
 
 
+static int query_inc (lua_State *L) {
+  global_State *g = G(L);
+  lua_pushinteger(L, gettotalobjs(g));
+  lua_pushinteger(L, g->GCdebt);
+  lua_pushinteger(L, getgcparam(g->gcpause));
+  lua_pushinteger(L, getgcparam(g->gcstepmul));
+  lua_pushinteger(L, cast(l_mem, 1) << g->gcstepsize);
+  return 5;
+}
+
 static int string_query (lua_State *L) {
   stringtable *tb = &G(L)->strt;
   int s = cast_int(luaL_optinteger(L, 1, 0)) - 1;
@@ -1933,6 +1943,7 @@ static const struct luaL_Reg tests_funcs[] = {
   {"pushuserdata", pushuserdata},
   {"querystr", string_query},
   {"querytab", table_query},
+  {"queryinc", query_inc},
   {"ref", tref},
   {"resume", coresume},
   {"s2d", s2d},

lua.c

@@ -633,7 +633,8 @@ static int pmain (lua_State *L) {
   }
   luaL_openlibs(L);  /* open standard libraries */
   createargtable(L, argv, argc, script);  /* create table 'arg' */
-  lua_gc(L, LUA_GCGEN, 0, 0);  /* GC in generational mode */
+  lua_gc(L, LUA_GCRESTART);  /* start GC... */
+  lua_gc(L, LUA_GCGEN, 0, 0);  /* ...in generational mode */
   if (!(args & has_E)) {  /* no option '-E'? */
     if (handle_luainit(L) != LUA_OK)  /* run LUA_INIT */
       return 0;  /* error running LUA_INIT */
@@ -665,6 +666,7 @@ int main (int argc, char **argv) {
     l_message(argv[0], "cannot create state: not enough memory");
     return EXIT_FAILURE;
   }
+  lua_gc(L, LUA_GCSTOP);  /* stop GC while buidling state */
   lua_pushcfunction(L, &pmain);  /* to call 'pmain' in protected mode */
   lua_pushinteger(L, argc);  /* 1st argument */
   lua_pushlightuserdata(L, argv); /* 2nd argument */