commit 2a66b34f720cdfb34e3455eb3dbc7fb8aa931981
parent 8d0e1ed52f4e5a4368343d3807140397176b577e
Author: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Sun, 20 May 2012 17:36:20 -0300
revamp of the GC pace control; more like 5.1: any X Kbytes allocated
makes the GC handle f(X) Kbytes of objects
Diffstat:
| M | lgc.c | | | 213 | +++++++++++++++++++++++++++++++++++++++++++------------------------------------ |
| M | lstate.h | | | 4 | +++- |
2 files changed, 120 insertions(+), 97 deletions(-)
diff --git a/lgc.c b/lgc.c
@@ -1,5 +1,5 @@
/*
-** $Id: lgc.c,v 2.121 2012/05/11 19:22:33 roberto Exp roberto $
+** $Id: lgc.c,v 2.122 2012/05/14 17:52:56 roberto Exp roberto $
** Garbage Collector
** See Copyright Notice in lua.h
*/
@@ -25,33 +25,36 @@
/* how much to allocate before next GC step */
-#define GCSTEPSIZE 1024
+#define GCSTEPSIZE (cast_int(256 * sizeof(void*)))
-/* maximum number of elements to sweep in each single step */
-#define GCSWEEPMAX 40
+/* cost of sweeping one element (half the size of a small object) */
+#define GCSWEEPCOST ((sizeof(TString) + 2) / 2)
-/* cost of sweeping one element */
-#define GCSWEEPCOST 1
+/* maximum number of elements to sweep in each single step */
+#define GCSWEEPMAX (cast_int((GCSTEPSIZE / GCSWEEPCOST) / 4))
/* maximum number of finalizers to call in each GC step */
#define GCFINALIZENUM 4
-/* cost of marking the root set */
-#define GCROOTCOST 10
-
-/* cost of atomic step */
-#define GCATOMICCOST 1000
+/* (arbitrary) cost of atomic step */
+#define GCATOMICCOST GCSTEPSIZE
-/* basic cost to traverse one object (to be added to the links the
- object may have) */
-#define TRAVCOST 5
+/*
+** macro to apply the "speed" of the garbage collector: the constant
+** 80 makes the standard 'stepmul' of 200 results in the GC handling
+** 80/200 = 1/2.5 = 0.4Kbytes for every 1Kb allocated.
+** (The computation tries to avoid overflows or underflows.)
+*/
+#define workrate(x,mul) \
+ ((x) < MAX_INT/80 ? ((x) * 80) / mul : ((x) / mul) * 80)
/*
** standard negative debt for GC; a reasonable "time" to wait before
** starting a new cycle
*/
-#define stddebt(g) (-cast(l_mem, gettotalbytes(g)/100) * g->gcpause)
+#define stddebtest(g,e) (-cast(l_mem, (e)/100) * g->gcpause)
+#define stddebt(g) stddebtest(g, gettotalbytes(g))
/*
@@ -244,53 +247,57 @@ GCObject *luaC_newobj (lua_State *L, int tt, size_t sz, GCObject **list,
** upvalues are already linked in 'headuv' list.)
*/
static void reallymarkobject (global_State *g, GCObject *o) {
+ lu_mem size;
white2gray(o);
switch (gch(o)->tt) {
case LUA_TSHRSTR:
case LUA_TLNGSTR: {
- gray2black(o);
- return; /* nothing else to mark */
+ size = sizestring(gco2ts(o));
+ break; /* nothing else to mark; make it black */
}
case LUA_TUSERDATA: {
Table *mt = gco2u(o)->metatable;
markobject(g, mt);
markobject(g, gco2u(o)->env);
- gray2black(o); /* all pointers marked */
- return;
+ size = sizeudata(gco2u(o));
+ break;
}
case LUA_TUPVAL: {
UpVal *uv = gco2uv(o);
markvalue(g, uv->v);
- if (uv->v == &uv->u.value) /* closed? (open upvalues remain gray) */
- gray2black(o); /* make it black */
- return;
+ if (uv->v != &uv->u.value) /* open? */
+ return; /* open upvalues remain gray */
+ size = sizeof(UpVal);
+ break;
}
case LUA_TLCL: {
gco2lcl(o)->gclist = g->gray;
g->gray = o;
- break;
+ return;
}
case LUA_TCCL: {
gco2ccl(o)->gclist = g->gray;
g->gray = o;
- break;
+ return;
}
case LUA_TTABLE: {
linktable(gco2t(o), &g->gray);
- break;
+ return;
}
case LUA_TTHREAD: {
gco2th(o)->gclist = g->gray;
g->gray = o;
- break;
+ return;
}
case LUA_TPROTO: {
gco2p(o)->gclist = g->gray;
g->gray = o;
- break;
+ return;
}
- default: lua_assert(0);
+ default: lua_assert(0); return;
}
+ gray2black(o);
+ g->GCmemtrav += size;
}
@@ -430,30 +437,26 @@ static void traversestrongtable (global_State *g, Table *h) {
}
-static int traversetable (global_State *g, Table *h) {
+static lu_mem traversetable (global_State *g, Table *h) {
+ char *weakkey, *weakvalue;
const TValue *mode = gfasttm(g, h->metatable, TM_MODE);
markobject(g, h->metatable);
- if (mode && ttisstring(mode)) { /* is there a weak mode? */
- int weakkey = (strchr(svalue(mode), 'k') != NULL);
- int weakvalue = (strchr(svalue(mode), 'v') != NULL);
- if (weakkey || weakvalue) { /* is really weak? */
- black2gray(obj2gco(h)); /* keep table gray */
- if (!weakkey) { /* strong keys? */
- traverseweakvalue(g, h);
- return TRAVCOST + sizenode(h);
- }
- else if (!weakvalue) { /* strong values? */
- traverseephemeron(g, h);
- return TRAVCOST + h->sizearray + sizenode(h);
- }
- else {
- linktable(h, &g->allweak); /* nothing to traverse now */
- return TRAVCOST;
- }
- } /* else go through */
+ if (mode && ttisstring(mode) && /* is there a weak mode? */
+ ((weakkey = strchr(svalue(mode), 'k')),
+ (weakvalue = strchr(svalue(mode), 'v')),
+ (weakkey || weakvalue))) { /* is really weak? */
+ black2gray(obj2gco(h)); /* keep table gray */
+ if (!weakkey) /* strong keys? */
+ traverseweakvalue(g, h);
+ else if (!weakvalue) /* strong values? */
+ traverseephemeron(g, h);
+ else /* all weak */
+ linktable(h, &g->allweak); /* nothing to traverse now */
}
- traversestrongtable(g, h);
- return TRAVCOST + h->sizearray + (2 * sizenode(h));
+ else /* not weak */
+ traversestrongtable(g, h);
+ return sizeof(Table) + sizeof(TValue) * h->sizearray +
+ sizeof(Node) * sizenode(h);
}
@@ -470,81 +473,92 @@ static int traverseproto (global_State *g, Proto *f) {
markobject(g, f->p[i]);
for (i = 0; i < f->sizelocvars; i++) /* mark local-variable names */
markobject(g, f->locvars[i].varname);
- return TRAVCOST + f->sizek + f->sizeupvalues + f->sizep + f->sizelocvars;
+ return sizeof(Proto) + sizeof(Instruction) * f->sizecode +
+ sizeof(Proto *) * f->sizep +
+ sizeof(TValue) * f->sizek +
+ sizeof(int) * f->sizelineinfo +
+ sizeof(LocVar) * f->sizelocvars +
+ sizeof(Upvaldesc) * f->sizeupvalues;
}
-static int traverseCclosure (global_State *g, CClosure *cl) {
+static lu_mem traverseCclosure (global_State *g, CClosure *cl) {
int i;
for (i = 0; i < cl->nupvalues; i++) /* mark its upvalues */
markvalue(g, &cl->upvalue[i]);
- return TRAVCOST + cl->nupvalues;
+ return sizeCclosure(cl->nupvalues);
}
-static int traverseLclosure (global_State *g, LClosure *cl) {
+static lu_mem traverseLclosure (global_State *g, LClosure *cl) {
int i;
markobject(g, cl->p); /* mark its prototype */
for (i = 0; i < cl->nupvalues; i++) /* mark its upvalues */
markobject(g, cl->upvals[i]);
- return TRAVCOST + cl->nupvalues;
+ return sizeLclosure(cl->nupvalues);
}
-static int traversestack (global_State *g, lua_State *L) {
- StkId o = L->stack;
+static lu_mem traversestack (global_State *g, lua_State *th) {
+ StkId o = th->stack;
if (o == NULL)
return 1; /* stack not completely built yet */
- for (; o < L->top; o++)
+ for (; o < th->top; o++)
markvalue(g, o);
if (g->gcstate == GCSatomic) { /* final traversal? */
- StkId lim = L->stack + L->stacksize; /* real end of stack */
+ StkId lim = th->stack + th->stacksize; /* real end of stack */
for (; o < lim; o++) /* clear not-marked stack slice */
setnilvalue(o);
}
- return TRAVCOST + cast_int(o - L->stack);
+ return sizeof(lua_State) + sizeof(TValue) * th->stacksize;
}
/*
** traverse one gray object, turning it to black (except for threads,
** which are always gray).
-** Returns number of values traversed.
*/
-static int propagatemark (global_State *g) {
+static void propagatemark (global_State *g) {
+ lu_mem size;
GCObject *o = g->gray;
lua_assert(isgray(o));
gray2black(o);
switch (gch(o)->tt) {
case LUA_TTABLE: {
Table *h = gco2t(o);
- g->gray = h->gclist;
- return traversetable(g, h);
+ g->gray = h->gclist; /* remove from 'gray' list */
+ size = traversetable(g, h);
+ break;
}
case LUA_TLCL: {
LClosure *cl = gco2lcl(o);
- g->gray = cl->gclist;
- return traverseLclosure(g, cl);
+ g->gray = cl->gclist; /* remove from 'gray' list */
+ size = traverseLclosure(g, cl);
+ break;
}
case LUA_TCCL: {
CClosure *cl = gco2ccl(o);
- g->gray = cl->gclist;
- return traverseCclosure(g, cl);
+ g->gray = cl->gclist; /* remove from 'gray' list */
+ size = traverseCclosure(g, cl);
+ break;
}
case LUA_TTHREAD: {
lua_State *th = gco2th(o);
- g->gray = th->gclist;
+ g->gray = th->gclist; /* remove from 'gray' list */
th->gclist = g->grayagain;
- g->grayagain = o;
+ g->grayagain = o; /* insert into 'grayagain' list */
black2gray(o);
- return traversestack(g, th);
+ size = traversestack(g, th);
+ break;
}
case LUA_TPROTO: {
Proto *p = gco2p(o);
- g->gray = p->gclist;
- return traverseproto(g, p);
+ g->gray = p->gclist; /* remove from 'gray' list */
+ size = traverseproto(g, p);
+ break;
}
- default: lua_assert(0); return 0;
+ default: lua_assert(0); return;
}
+ g->GCmemtrav += size;
}
@@ -706,7 +720,6 @@ static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count) {
int ow = otherwhite(g);
int toclear, toset; /* bits to clear and to set in all live objects */
int tostop; /* stop sweep when this is true */
- l_mem debt = g->GCdebt; /* current debt */
if (isgenerational(g)) { /* generational mode? */
toclear = ~0; /* clear nothing */
toset = bitmask(OLDBIT); /* set the old bit of all surviving objects */
@@ -737,7 +750,6 @@ static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count) {
p = &gch(curr)->next; /* go to next element */
}
}
- luaE_setdebt(g, debt); /* sweeping should not change debt */
return p;
}
@@ -960,37 +972,42 @@ static void atomic (lua_State *L) {
}
-static l_mem singlestep (lua_State *L) {
+static lu_mem singlestep (lua_State *L) {
global_State *g = G(L);
switch (g->gcstate) {
case GCSpause: {
+ g->GCmemtrav = 0; /* start to count memory traversed */
if (!isgenerational(g))
markroot(g); /* start a new collection */
- /* in any case, root must be marked */
+ /* in any case, root must be marked at this point */
lua_assert(!iswhite(obj2gco(g->mainthread))
&& !iswhite(gcvalue(&g->l_registry)));
g->gcstate = GCSpropagate;
- return GCROOTCOST;
+ return g->GCmemtrav;
}
case GCSpropagate: {
- if (g->gray)
- return propagatemark(g);
+ if (g->gray) {
+ lu_mem oldtrav = g->GCmemtrav;
+ propagatemark(g);
+ return g->GCmemtrav - oldtrav; /* memory traversed in this step */
+ }
else { /* no more `gray' objects */
g->gcstate = GCSatomic; /* finish mark phase */
+ g->estimate = g->GCmemtrav; /* save what was counted */
atomic(L);
return GCATOMICCOST;
}
}
case GCSsweepstring: {
- if (g->sweepstrgc < g->strt.size) {
- sweepwholelist(L, &g->strt.hash[g->sweepstrgc++]);
- return GCSWEEPCOST;
- }
- else { /* no more strings to sweep */
+ int i;
+ for (i = 0; i < GCSWEEPMAX && g->sweepstrgc + i < g->strt.size; i++)
+ sweepwholelist(L, &g->strt.hash[g->sweepstrgc + i]);
+ g->sweepstrgc += i;
+ if (g->sweepstrgc >= g->strt.size) { /* no more strings to sweep? */
g->sweepgc = &g->finobj; /* prepare to sweep finalizable objects */
g->gcstate = GCSsweepudata;
- return 0;
}
+ return i * GCSWEEPCOST;
}
case GCSsweepudata: {
if (*g->sweepgc) {
@@ -1000,7 +1017,7 @@ static l_mem singlestep (lua_State *L) {
else {
g->sweepgc = &g->allgc; /* go to next phase */
g->gcstate = GCSsweep;
- return GCSWEEPCOST;
+ return 0;
}
}
case GCSsweep: {
@@ -1051,14 +1068,17 @@ static void generationalcollection (lua_State *L) {
static void step (lua_State *L) {
global_State *g = G(L);
- l_mem lim = g->gcstepmul; /* how much to work */
+ l_mem debt = g->GCdebt;
+ int stepmul = g->gcstepmul;
+ if (stepmul <= 0) stepmul = 1;
do { /* always perform at least one single step */
- lim -= singlestep(L);
- } while (lim > 0 && g->gcstate != GCSpause);
- if (g->gcstate != GCSpause)
- luaE_setdebt(g, g->GCdebt - GCSTEPSIZE);
- else
- luaE_setdebt(g, stddebt(g));
+ lu_mem work = singlestep(L); /* do some work */
+ work = workrate(work, stepmul); /* apply work rate */
+ debt -= work;
+ } while (debt > -GCSTEPSIZE && g->gcstate != GCSpause);
+ if (g->gcstate == GCSpause)
+ debt = stddebtest(g, g->estimate); /* pause until next cycle */
+ luaE_setdebt(g, debt);
}
@@ -1070,8 +1090,9 @@ void luaC_step (lua_State *L) {
int i;
if (isgenerational(g)) generationalcollection(L);
else step(L);
- for (i = 0; i < GCFINALIZENUM && g->tobefnz; i++)
- GCTM(L, 1); /* Call a few pending finalizers */
+ /* run a few finalizers (or all of them at the end of a collect cycle) */
+ for (i = 0; g->tobefnz && (i < GCFINALIZENUM || g->gcstate == GCSpause); i++)
+ GCTM(L, 1); /* call one finalizer */
}
diff --git a/lstate.h b/lstate.h
@@ -1,5 +1,5 @@
/*
-** $Id: lstate.h,v 2.76 2012/01/25 21:05:40 roberto Exp roberto $
+** $Id: lstate.h,v 2.77 2012/02/01 21:57:15 roberto Exp roberto $
** Global State
** See Copyright Notice in lua.h
*/
@@ -113,7 +113,9 @@ typedef struct global_State {
void *ud; /* auxiliary data to `frealloc' */
lu_mem totalbytes; /* number of bytes currently allocated - GCdebt */
l_mem GCdebt; /* bytes allocated not yet compensated by the collector */
+ lu_mem GCmemtrav; /* memory traversed by the GC */
lu_mem lastmajormem; /* memory in use after last major collection */
+ lu_mem estimate;
stringtable strt; /* hash table for strings */
TValue l_registry;
unsigned int seed; /* randomized seed for hashes */
