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more precise control for GC pause (based on threshold)

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Roberto Ierusalimschy 2012-10-19 16:00:33 -03:00
parent 4082c77ff2
commit a799ed5af9
1 changed files with 27 additions and 19 deletions
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46
lgc.c
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@ -1,5 +1,5 @@
/*
** $Id: lgc.c,v 2.136 2012/09/11 12:53:08 roberto Exp roberto $
** $Id: lgc.c,v 2.137 2012/10/03 12:36:17 roberto Exp roberto $
** Garbage Collector
** See Copyright Notice in lua.h
*/
@ -43,21 +43,12 @@
*/
#define STEPMULADJ 200
/*
** macro to adjust 'pause': 'pause' is actually used like
** 'pause / PAUSEADJ' (value chosen by tests)
*/
#define PAUSEADJ 200
/*
** standard negative debt for GC; a reasonable "time" to wait before
** starting a new cycle
*/
#define stddebtest(g,e) (-cast(l_mem, (e)/PAUSEADJ) * g->gcpause)
#define stddebt(g) stddebtest(g, gettotalbytes(g))
#define PAUSEADJ 100
/*
@ -908,6 +899,21 @@ void luaC_checkfinalizer (lua_State *L, GCObject *o, Table *mt) {
*/
/*
** set a reasonable "time" to wait before starting a new GC cycle;
** cycle will start when memory use hits threshold
*/
static void setpause (global_State *g, l_mem estimate) {
l_mem debt, threshold;
estimate = estimate / PAUSEADJ; /* adjust 'estimate' */
threshold = (g->gcpause < MAX_LMEM / estimate) /* overflow? */
? estimate * g->gcpause /* no overflow */
: MAX_LMEM; /* overflow; truncate to maximum */
debt = -cast(l_mem, threshold - gettotalbytes(g));
luaE_setdebt(g, debt);
}
#define sweepphases \
(bitmask(GCSsweepstring) | bitmask(GCSsweepudata) | bitmask(GCSsweep))
@ -1028,7 +1034,8 @@ 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 */
/* start to count memory traversed */
g->GCmemtrav = g->strt.size * sizeof(GCObject*);
lua_assert(!isgenerational(g));
restartcollection(g);
g->gcstate = GCSpropagate;
@ -1117,7 +1124,7 @@ static void generationalcollection (lua_State *L) {
g->GCestimate = estimate; /* keep estimate from last major coll. */
}
luaE_setdebt(g, stddebt(g));
setpause(g, gettotalbytes(g));
lua_assert(g->gcstate == GCSpropagate);
}
@ -1126,7 +1133,7 @@ static void incstep (lua_State *L) {
global_State *g = G(L);
l_mem debt = g->GCdebt;
int stepmul = g->gcstepmul;
if (stepmul < 40) stepmul = 40; /* avoid ridiculous low values */
if (stepmul < 40) stepmul = 40; /* avoid ridiculous low values (and 0) */
/* convert debt from Kb to 'work units' (avoid zero debt and overflows) */
debt = (debt / STEPMULADJ) + 1;
debt = (debt < MAX_LMEM / stepmul) ? debt * stepmul : MAX_LMEM;
@ -1135,10 +1142,11 @@ static void incstep (lua_State *L) {
debt -= work;
} while (debt > -GCSTEPSIZE && g->gcstate != GCSpause);
if (g->gcstate == GCSpause)
debt = stddebtest(g, g->GCestimate); /* pause until next cycle */
else
setpause(g, g->GCestimate); /* pause until next cycle */
else {
debt = (debt / stepmul) * STEPMULADJ; /* convert 'work units' to Kb */
luaE_setdebt(g, debt);
luaE_setdebt(g, debt);
}
}
@ -1195,7 +1203,7 @@ void luaC_fullgc (lua_State *L, int isemergency) {
luaC_runtilstate(L, bitmask(GCSpropagate));
}
g->gckind = origkind;
luaE_setdebt(g, stddebt(g));
setpause(g, gettotalbytes(g));
if (!isemergency) /* do not run finalizers during emergency GC */
callallpendingfinalizers(L, 1);
}