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Chez Scheme GC: add ephemeron checking to parallel phase

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This commit is contained in:
Matthew Flatt 2020-09-19 07:09:37 -06:00
parent 7738499c70
commit 4ee149d226
3 changed files with 61 additions and 67 deletions
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99
racket/src/ChezScheme/c/gc.c
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@ -200,13 +200,13 @@ static void resweep_dirty_weak_pairs PROTO((ptr tc));
static void mark_typemod_data_object PROTO((ptr tc_in, ptr p, uptr len, seginfo *si));
static void add_pending_guardian PROTO((ptr gdn, ptr tconc));
static void add_trigger_guardians_to_recheck PROTO((ptr ls));
static void add_ephemeron_to_pending PROTO((ptr p));
static void add_trigger_ephemerons_to_pending PROTO((ptr p));
static void check_triggers PROTO((seginfo *si));
static void add_ephemeron_to_pending PROTO((ptr tc, ptr p));
static void add_trigger_ephemerons_to_pending PROTO((ptr tc, ptr p));
static void check_triggers PROTO((ptr tc, seginfo *si));
static void check_ephemeron PROTO((ptr tc_in, ptr pe));
static void check_pending_ephemerons PROTO((ptr tc_in));
static int check_dirty_ephemeron PROTO((ptr tc_in, ptr pe, int youngest));
static void finish_pending_ephemerons PROTO((seginfo *si));
static void finish_pending_ephemerons PROTO((ptr tc, seginfo *si));
static void init_fully_marked_mask(ptr tc_in, IGEN g);
static void copy_and_clear_list_bits(ptr tc_in, seginfo *oldspacesegments);
@ -225,7 +225,7 @@ static void init_measure_mask(ptr tc_in, seginfo *si);
static void init_counting_mask(ptr tc_in, seginfo *si);
static void push_measure(ptr tc_in, ptr p);
static void measure_add_stack_size(ptr stack, uptr size);
static void add_ephemeron_to_pending_measure(ptr pe);
static void add_ephemeron_to_pending_measure(ptr tc, ptr pe);
static void add_trigger_ephemerons_to_pending_measure(ptr pe);
static void check_ephemeron_measure(ptr tc_in, ptr pe);
static void check_pending_measure_ephemerons(ptr tc_in);
@ -623,15 +623,6 @@ static void do_relocate_pure_now(ptr tc_in, ptr *pp) {
}
}
static void do_relocate_impure_now(ptr tc_in, ptr *pp, IGEN g) {
ENABLE_LOCK_ACQUIRE
relocate_impure(pp, g);
while (CHECK_LOCK_FAILED(tc_in)) {
CLEAR_LOCK_FAILED(tc_in);
relocate_impure(pp, g);
}
}
static void do_mark_or_copy_pure_now(ptr tc_in, ptr *dest, ptr pp, seginfo *si) {
do {
CLEAR_LOCK_FAILED(tc_in);
@ -640,7 +631,6 @@ static void do_mark_or_copy_pure_now(ptr tc_in, ptr *dest, ptr pp, seginfo *si)
}
# define relocate_pure_now(pp) do_relocate_pure_now(tc_in, pp)
# define relocate_impure_now(pp, g) do_relocate_impure_now(tc_in, pp, g)
# define mark_or_copy_pure_now(dest, pp, si) do_mark_or_copy_pure_now(tc, dest, pp, si)
static void sweep_thread_now(ptr tc_in, ptr p) {
@ -652,12 +642,11 @@ static void sweep_thread_now(ptr tc_in, ptr p) {
#else
# define relocate_pure_now(pp) relocate_pure(pp)
# define relocate_impure_now(pp, g) relocate_impure(pp, g)
# define mark_or_copy_pure_now(tc, pp, si) mark_or_copy_pure(tc, pp, si)
# define sweep_thread_now(tc, thread) sweep_thread(tc, thread)
#endif
FORCEINLINE void check_triggers(seginfo *si) {
FORCEINLINE void check_triggers(ptr tc_in, seginfo *si) {
/* Registering ephemerons and guardians to recheck at the
granularity of a segment means that the worst-case complexity of
GC is quadratic in the number of objects that fit into a segment
@ -666,7 +655,7 @@ FORCEINLINE void check_triggers(seginfo *si) {
ephemerons). */
if (si->has_triggers) {
if (si->trigger_ephemerons) {
add_trigger_ephemerons_to_pending(si->trigger_ephemerons);
add_trigger_ephemerons_to_pending(tc_in, si->trigger_ephemerons);
si->trigger_ephemerons = 0;
}
if (si->trigger_guardians) {
@ -1493,7 +1482,7 @@ ptr GCENTRY(ptr tc_in, ptr count_roots_ls) {
resweep_weak_pairs(tc, oldweakspacesegments);
/* still-pending ephemerons all go to bwp */
finish_pending_ephemerons(oldspacesegments);
finish_pending_ephemerons(tc, oldspacesegments);
/* post-gc oblist handling. rebuild old buckets in the target generation, pruning unforwarded symbols */
{ bucket_list *bl; bucket *b, *bnext; bucket_pointer_list *bpl; bucket **pb; ptr sym;
@ -1933,7 +1922,7 @@ static iptr sweep_generation_pass(ptr tc_in) {
sweep_space(space_ephemeron, from_g, {
p = TYPE(TO_PTR(pp), type_pair);
add_ephemeron_to_pending(p);
add_ephemeron_to_pending(tc_in, p);
pp += size_ephemeron / sizeof(ptr);
})
@ -1986,6 +1975,12 @@ static iptr sweep_generation_pass(ptr tc_in) {
/* don't sweep from space_count_pure or space_count_impure */
}
/* Waiting until sweeping doesn't trigger a change reduces the
chance that an ephemeron must be reigistered as a
segment-specific trigger or gets triggered for recheck, but
it doesn't change the worst-case complexity. */
if (SWEEPCHANGE(tc_in) == SWEEP_NO_CHANGE)
check_pending_ephemerons(tc_in);
} while (SWEEPCHANGE(tc_in) == SWEEP_CHANGE_PROGRESS);
return num_swept_bytes;
@ -1994,12 +1989,6 @@ static iptr sweep_generation_pass(ptr tc_in) {
static void sweep_generation(ptr tc_in) {
do {
sweep_generation_pass(tc_in);
/* Waiting until sweeping doesn't trigger a change reduces the
chance that an ephemeron must be reigistered as a
segment-specific trigger or gets triggered for recheck, but
it doesn't change the worst-case complexity. */
check_pending_ephemerons(tc_in);
} while (SWEEPCHANGE(tc_in) != SWEEP_NO_CHANGE);
}
@ -2572,9 +2561,6 @@ static void add_trigger_guardians_to_recheck(ptr ls)
GC_TC_MUTEX_RELEASE();
}
static ptr pending_ephemerons = 0;
/* Ephemerons that we haven't looked at, chained through `next`. */
static void ephemeron_remove(ptr pe) {
ptr next = EPHEMERONNEXT(pe);
*((ptr *)TO_VOIDP(EPHEMERONPREVREF(pe))) = next;
@ -2598,25 +2584,22 @@ static void ephemeron_add(ptr *first, ptr pe) {
EPHEMERONPREVREF(next) = TO_PTR(&EPHEMERONNEXT(last_pe));
}
static void add_ephemeron_to_pending(ptr pe) {
static void add_ephemeron_to_pending(ptr tc_in, ptr pe) {
/* We could call check_ephemeron directly here, but the indirection
through `pending_ephemerons` can dramatically decrease the number
through `PENDINGEPHEMERONS` can dramatically decrease the number
of times that we have to trigger re-checking, especially since
check_pending_pehemerons() is run only after all other sweep
opportunities are exhausted. */
GC_TC_MUTEX_ACQUIRE();
if (EPHEMERONPREVREF(pe)) ephemeron_remove(pe);
ephemeron_add(&pending_ephemerons, pe);
GC_TC_MUTEX_RELEASE();
ephemeron_add(&PENDINGEPHEMERONS(tc_in), pe);
}
static void add_trigger_ephemerons_to_pending(ptr pe) {
GC_TC_MUTEX_ACQUIRE();
ephemeron_add(&pending_ephemerons, pe);
GC_TC_MUTEX_RELEASE();
static void add_trigger_ephemerons_to_pending(ptr tc_in, ptr pe) {
ephemeron_add(&PENDINGEPHEMERONS(tc_in), pe);
}
static void check_ephemeron(ptr tc_in, ptr pe) {
ENABLE_LOCK_ACQUIRE
ptr p;
seginfo *si;
IGEN from_g;
@ -2629,41 +2612,55 @@ static void check_ephemeron(ptr tc_in, ptr pe) {
p = Scar(pe);
if (!IMMEDIATE(p) && (si = MaybeSegInfo(ptr_get_segment(p))) != NULL && si->old_space) {
if (SEGMENT_LOCK_ACQUIRE(si)) {
if (new_marked(si, p)) {
ENABLE_LOCK_ACQUIRE /* for nested relocate */
#ifndef NO_DIRTY_NEWSPACE_POINTERS
IGEN tg = TARGET_GENERATION(si);
if (tg < from_g) S_record_new_dirty_card(tc_in, &INITCAR(pe), tg);
#endif
relocate_impure_now(&INITCDR(pe), from_g);
relocate_impure(&INITCDR(pe), from_g);
} else if (FORWARDEDP(p, si)) {
ENABLE_LOCK_ACQUIRE /* for nested relocate */
#ifndef NO_DIRTY_NEWSPACE_POINTERS
IGEN tg = TARGET_GENERATION(si);
if (tg < from_g) S_record_new_dirty_card(tc_in, &INITCAR(pe), tg);
#endif
INITCAR(pe) = FWDADDRESS(p);
relocate_impure_now(&INITCDR(pe), from_g);
relocate_impure(&INITCDR(pe), from_g);
} else {
/* If we get here, then there's no lock failure: */
/* Not reached, so far; install as trigger */
ephemeron_add(&si->trigger_ephemerons, pe);
si->has_triggers = 1;
}
SEGMENT_LOCK_RELEASE(si);
} else {
relocate_impure_now(&INITCDR(pe), from_g);
RECORD_LOCK_FAILED(tc_in, si);
}
} else {
relocate_impure(&INITCDR(pe), from_g);
}
POP_BACKREFERENCE();
}
/* non-parallel: */
static void check_pending_ephemerons(ptr tc_in) {
ptr pe, next_pe;
pe = pending_ephemerons;
pending_ephemerons = 0;
pe = PENDINGEPHEMERONS(tc_in);
PENDINGEPHEMERONS(tc_in) = 0;
while (pe != 0) {
next_pe = EPHEMERONNEXT(pe);
check_ephemeron(tc_in, pe);
if (CHECK_LOCK_FAILED(tc_in)) {
CLEAR_LOCK_FAILED(tc_in);
SWEEPCHANGE(tc_in) = SWEEP_CHANGE_POSTPONED;
EPHEMERONNEXT(pe) = next_pe;
ephemeron_add(&PENDINGEPHEMERONS(tc_in), pe);
break;
}
pe = next_pe;
}
}
@ -2690,7 +2687,7 @@ static IGEN check_dirty_ephemeron(ptr tc_in, ptr pe, IGEN youngest) {
relocate_dirty(&INITCDR(pe), youngest);
} else {
/* Not reached, so far; add to pending list */
add_ephemeron_to_pending(pe);
add_ephemeron_to_pending(tc_in, pe);
/* Make the consistent (but pessimistic w.r.t. to wrong-way
pointers) assumption that the key will stay live and move
@ -2721,10 +2718,10 @@ static IGEN check_dirty_ephemeron(ptr tc_in, ptr pe, IGEN youngest) {
return youngest;
}
static void finish_pending_ephemerons(seginfo *si) {
static void finish_pending_ephemerons(ptr tc_in, seginfo *si) {
/* Any ephemeron still in a trigger list is an ephemeron
whose key was not reached. */
if (pending_ephemerons != 0)
if (PENDINGEPHEMERONS(tc_in) != 0)
S_error_abort("clear_trigger_ephemerons(gc): non-empty pending list");
for (; si != NULL; si = si->next) {
@ -3004,10 +3001,6 @@ static void parallel_sweep_dirty_and_generation(ptr tc) {
s_thread_mutex_unlock(&sweep_mutex);
S_use_gc_tc_mutex = 0;
/* check ephemerons and finish in non-parallel mode */
check_pending_ephemerons(tc);
sweep_generation(tc);
}
#define WAIT_AFTER_POSTPONES 100
@ -3156,7 +3149,7 @@ static void measure_add_stack_size(ptr stack, uptr size) {
measure_total += size;
}
static void add_ephemeron_to_pending_measure(ptr pe) {
static void add_ephemeron_to_pending_measure(ptr tc_in, ptr pe) {
/* If we're in hybrid mode and the key in `pe` is in the
old space, then we need to use the regular pending list
instead of the measure-specific one */
@ -3164,7 +3157,7 @@ static void add_ephemeron_to_pending_measure(ptr pe) {
ptr p = Scar(pe);
if (!IMMEDIATE(p) && (si = MaybeSegInfo(ptr_get_segment(p))) != NULL && si->old_space)
add_ephemeron_to_pending(pe);
add_ephemeron_to_pending(tc_in, pe);
else {
if (EPHEMERONPREVREF(pe))
S_error_abort("add_ephemeron_to_pending_measure: ephemeron is in some list");

1
racket/src/ChezScheme/s/cmacros.ss
View File

@ -1579,6 +1579,7 @@
[iptr bytes-left (constant num-thread-local-allocation-segments)]
[xptr sweep-loc (constant num-thread-local-allocation-segments)]
[xptr sweep-next (constant num-thread-local-allocation-segments)]
[xptr pending-ephemerons]
[iptr sweeper]
[xptr sweep-stack]
[xptr sweep-stack-start]

8
racket/src/ChezScheme/s/mkgc.ss
View File

@ -662,9 +662,9 @@
(define-trace-macro (add-ephemeron-to-pending)
(case-mode
[(sweep mark)
(add_ephemeron_to_pending _)]
(add_ephemeron_to_pending _tc_ _)]
[measure
(add_ephemeron_to_pending_measure _)]
(add_ephemeron_to_pending_measure _tc_ _)]
[else]))
(define-trace-macro (assert-ephemeron-size-ok)
@ -1424,7 +1424,7 @@
(code-block
"ENABLE_LOCK_ACQUIRE"
"if (CHECK_LOCK_FAILED(tc_in)) return 0xff;"
"check_triggers(si);"
"check_triggers(tc_in, si);"
(code-block
"ptr new_p;"
"IGEN tg = TARGET_GENERATION(si);"
@ -1441,7 +1441,7 @@
(code-block
"ENABLE_LOCK_ACQUIRE"
"if (CHECK_LOCK_FAILED(tc_in)) return 0xff;"
"check_triggers(si);"
"check_triggers(tc_in, si);"
(ensure-segment-mark-mask "si" "" '())
(body)
"SWEEPCHANGE(tc_in) = SWEEP_CHANGE_PROGRESS;"