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xo-alloc: try to make commit happen at start of GC cycle

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This commit is contained in:
Roland Conybeare 2025-08-26 13:36:18 -04:00
commit 6c7b13e443
4 changed files with 77 additions and 48 deletions
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88
src/alloc/GC.cpp
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@ -68,16 +68,23 @@ namespace xo {
nursery_[role2int(role::from_space)]
= ArenaAlloc::make("NA", nursery_size, config.debug_flag_);
nursery_[role2int(role::to_space) ]
= ArenaAlloc::make("NB", nursery_size, config.debug_flag_);
tenured_[role2int(role::from_space)]
= ArenaAlloc::make("TA", tenured_size, config.debug_flag_);
tenured_[role2int(role::to_space) ]
= ArenaAlloc::make("TB", tenured_size, config.debug_flag_);
nursery_[role2int(role::from_space)]->expand(config.incr_gc_threshold_);
nursery_[role2int(role::to_space) ]->expand(config.incr_gc_threshold_);
tenured_[role2int(role::from_space)]->expand(config.full_gc_threshold_);
tenured_[role2int(role::to_space) ]->expand(config.full_gc_threshold_);
mutation_log_[role2int(role::from_space)] = std::make_unique<MutationLog>();
mutation_log_[role2int(role::to_space)] = std::make_unique<MutationLog>();
mutation_log_[role2int(role::to_space )] = std::make_unique<MutationLog>();
defer_mutation_log_ = std::make_unique<MutationLog>();
this->gc_history_ = CircularBuffer<GcStatisticsHistoryItem>(config.stats_history_z_);
@ -194,6 +201,12 @@ namespace xo {
return retval;
}
std::size_t
GC::nursery_from_allocated() const
{
return nursery_from()->allocated();
}
std::size_t
GC::nursery_to_reserved() const
{
@ -259,7 +272,7 @@ namespace xo {
return generation_result::not_found;
}
std::tuple<generation_result, std::size_t, std::size_t>
std::tuple<generation_result, std::size_t, std::size_t, std::size_t>
GC::location_of(role role, const void *x) const
{
{
@ -267,7 +280,7 @@ namespace xo {
auto [is_tenured, offset] = space->location_of(x);
if (is_tenured)
return std::make_tuple(generation_result::tenured, offset, space->allocated());
return std::make_tuple(generation_result::tenured, offset, space->allocated(), space->committed());
}
{
@ -275,19 +288,19 @@ namespace xo {
auto [is_nursery, offset] = nursery(role)->location_of(x);
if (is_nursery)
return std::make_tuple(generation_result::nursery, offset, space->allocated());
return std::make_tuple(generation_result::nursery, offset, space->allocated(), space->committed());
}
return std::make_tuple(generation_result::not_found, 0, 0);
return std::make_tuple(generation_result::not_found, 0, 0, 0);
}
std::tuple<generation_result, std::size_t, std::size_t>
std::tuple<generation_result, std::size_t, std::size_t, std::size_t>
GC::tospace_location_of(const void * x) const
{
return location_of(role::to_space, x);
}
std::tuple<generation_result, std::size_t, std::size_t>
std::tuple<generation_result, std::size_t, std::size_t, std::size_t>
GC::fromspace_location_of(const void * x) const
{
return location_of(role::from_space, x);
@ -533,29 +546,26 @@ namespace xo {
*/
std::size_t max_promote_z = nursery_[role2int(role::to_space)]->before_checkpoint();
log && log(xtag("max_promote_z", max_promote_z));
ArenaAlloc * tenured_to = this->tenured_to();
/* tenured generation may need this much space */
std::size_t need_tenured_z = (tenured_to->allocated()
+ max_promote_z
+ config_.full_gc_threshold_);
log && log(xtag("alloc_tenured_z", tenured_to->allocated()),
xtag("max_promote_z", max_promote_z),
xtag("full_gc_threshold", config_.full_gc_threshold_),
xtag("need_tenured_z", need_tenured_z));
tenured_to->expand(tenured_to->allocated()
+ max_promote_z
+ config_.full_gc_threshold_);
if (target == generation::tenured) {
/* gc on tenured generation may need this much space */
std::size_t need_tenured_z = (tenured_[role2int(role::to_space)]->allocated()
+ max_promote_z
+ config_.full_gc_threshold_);
log && log("need_tenured_z", need_tenured_z);
tenured_from()->reset(need_tenured_z);
tenured_from()->clear();
this->swap_tenured();
} else {
std::size_t avail_tenured_z = tenured_[role2int(role::to_space)]->available();
log && log(xtag("avail_tenured_z", avail_tenured_z));
if (avail_tenured_z < max_promote_z) {
ArenaAlloc * tenured_to = this->tenured_to();
tenured_to->expand(max_promote_z);
}
}
/* subtracting max_promote_z is correct here, since anything not promoted is garbage */
@ -1220,24 +1230,22 @@ namespace xo {
void
GC::request_gc(generation target)
{
/** full collection when >= @ref full_gc_threshold_ bytes added to tenured
* generation, since last full collection
**/
bool need_full_gc
= ((target == generation::tenured)
|| (this->tenured_to()->after_checkpoint() > config_.full_gc_threshold_)
|| !config_.allow_incremental_gc_);
if (need_full_gc)
target = generation::tenured;
if (!runstate_.in_progress() && (gc_enabled_ == 0)) {
if (!config_.allow_incremental_gc_)
target = generation::tenured;
if ((target == generation::nursery)
&& (this->tenured_to()->after_checkpoint() > config_.full_gc_threshold_))
{
/** full collection when >= @ref full_gc_threshold_ bytes added to tenured
* generation, since last full collection
**/
target = generation::tenured;
}
this->execute_gc(target);
} else {
this->incr_gc_pending_ = true;
if (target == generation::tenured)
this->full_gc_pending_ = true;
this->full_gc_pending_ |= need_full_gc;
}
}