From 2a66b34f720cdfb34e3455eb3dbc7fb8aa931981 Mon Sep 17 00:00:00 2001 From: Roberto Ierusalimschy Date: Sun, 20 May 2012 17:36:44 -0300 Subject: revamp of the GC pace control; more like 5.1: any X Kbytes allocated makes the GC handle f(X) Kbytes of objects --- lgc.c | 213 +++++++++++++++++++++++++++++++++++---------------------------- lstate.h | 4 +- 2 files changed, 120 insertions(+), 97 deletions(-) diff --git a/lgc.c b/lgc.c index ef8646c7..219d86d9 100644 --- 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 index f6c093b3..85359fe3 100644 --- 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 */ -- cgit v1.2.3-55-g6feb