From 8d4feb504f34c182ad991102d5ccd974b3a5f1b8 Mon Sep 17 00:00:00 2001
From: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Thu, 31 Mar 2016 16:02:03 -0300
Subject: do not try to ensure that 'sweepgc' points to a live object when
entering sweep phase ('entersweep'); that may be too expensive to be done
still inside the atomic step. Walking one single object more often than not
will work.
---
lgc.c | 29 +++++++++++------------------
1 file changed, 11 insertions(+), 18 deletions(-)
diff --git a/lgc.c b/lgc.c
index 55c1e4f6..5eae15d7 100644
--- a/lgc.c
+++ b/lgc.c
@@ -1,5 +1,5 @@
/*
-** $Id: lgc.c,v 2.210 2015/11/03 18:10:44 roberto Exp roberto $
+** $Id: lgc.c,v 2.211 2015/12/10 18:12:30 roberto Exp roberto $
** Garbage Collector
** See Copyright Notice in lua.h
*/
@@ -754,14 +754,11 @@ static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count) {
/*
** sweep a list until a live object (or end of list)
*/
-static GCObject **sweeptolive (lua_State *L, GCObject **p, int *n) {
+static GCObject **sweeptolive (lua_State *L, GCObject **p) {
GCObject **old = p;
- int i = 0;
do {
- i++;
p = sweeplist(L, p, 1);
} while (p == old);
- if (n) *n += i;
return p;
}
@@ -909,7 +906,7 @@ void luaC_checkfinalizer (lua_State *L, GCObject *o, Table *mt) {
if (issweepphase(g)) {
makewhite(g, o); /* "sweep" object 'o' */
if (g->sweepgc == &o->next) /* should not remove 'sweepgc' object */
- g->sweepgc = sweeptolive(L, g->sweepgc, NULL); /* change 'sweepgc' */
+ g->sweepgc = sweeptolive(L, g->sweepgc); /* change 'sweepgc' */
}
/* search for pointer pointing to 'o' */
for (p = &g->allgc; *p != o; p = &(*p)->next) { /* empty */ }
@@ -951,19 +948,16 @@ static void setpause (global_State *g) {
/*
** Enter first sweep phase.
-** The call to 'sweeptolive' makes pointer point to an object inside
-** the list (instead of to the header), so that the real sweep do not
-** need to skip objects created between "now" and the start of the real
-** sweep.
-** Returns how many objects it swept.
+** The call to 'sweeplist' tries to make pointer point to an object
+** inside the list (instead of to the header), so that the real sweep do
+** not need to skip objects created between "now" and the start of the
+** real sweep.
*/
-static int entersweep (lua_State *L) {
+static void entersweep (lua_State *L) {
global_State *g = G(L);
- int n = 0;
g->gcstate = GCSswpallgc;
lua_assert(g->sweepgc == NULL);
- g->sweepgc = sweeptolive(L, &g->allgc, &n);
- return n;
+ g->sweepgc = sweeplist(L, &g->allgc, 1);
}
@@ -1064,12 +1058,11 @@ static lu_mem singlestep (lua_State *L) {
}
case GCSatomic: {
lu_mem work;
- int sw;
propagateall(g); /* make sure gray list is empty */
work = atomic(L); /* work is what was traversed by 'atomic' */
- sw = entersweep(L);
+ entersweep(L);
g->GCestimate = gettotalbytes(g); /* first estimate */;
- return work + sw * GCSWEEPCOST;
+ return work;
}
case GCSswpallgc: { /* sweep "regular" objects */
return sweepstep(L, g, GCSswpfinobj, &g->finobj);
--
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