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variable.c: reduce heap usage for autoload_data_i

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For the loader (first thread which hits autoload, it is wasteful
to have extra elements on the stack.  For the lifetime of the
process, it is wasteful to waste 2 words for every autoload
entry.  So this makes full use of existing stack overhead
while reducing heap overhead for long-lived autoload_data_i
structs.

* variable.c (struct autoload_state): usable as wait-queue head
  (struct autoload_data_i): remove 2 words of overhead
  (autoload_i_mark): remove marking for thread
  (autoload_reset): adjust for struct changes
  (rb_autoload): ditto
  (rb_autoloading_value): ditto
  (rb_autoload_load): ditto
  (const_update): ditto

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@52335 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
This commit is contained in:
normal 2015-10-29 01:14:45 +00:00
parent d90f9b1481
commit fc87b3b7e0
2 changed files with 42 additions and 30 deletions
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11
ChangeLog
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@ -1,3 +1,14 @@
Thu Oct 29 10:08:33 2015 Eric Wong <e@80x24.org>
* variable.c (struct autoload_state): usable as wait-queue head
(struct autoload_data_i): remove 2 words of overhead
(autoload_i_mark): remove marking for thread
(autoload_reset): adjust for struct changes
(rb_autoload): ditto
(rb_autoloading_value): ditto
(rb_autoload_load): ditto
(const_update): ditto
Thu Oct 29 08:48:05 2015 Eric Wong <e@80x24.org> Thu Oct 29 08:48:05 2015 Eric Wong <e@80x24.org>
* variable.c (struct autoload_data_i): add waitq_head * variable.c (struct autoload_data_i): add waitq_head

61
variable.c
View File

@ -1892,12 +1892,24 @@ autoload_data(VALUE mod, ID id)
return (VALUE)val; return (VALUE)val;
} }
/* always on stack, no need to mark */
struct autoload_state {
struct autoload_data_i *ele;
VALUE mod;
VALUE result;
ID id;
VALUE thread;
union {
struct list_node node;
struct list_head head;
} waitq;
};
struct autoload_data_i { struct autoload_data_i {
VALUE feature; VALUE feature;
int safe_level; int safe_level;
VALUE thread;
VALUE value; VALUE value;
struct list_head waitq_head; /* links autoload_state.waitq_node */ struct autoload_state *state; /* points to on-stack struct */
}; };
static void static void
@ -1905,7 +1917,6 @@ autoload_i_mark(void *ptr)
{ {
struct autoload_data_i *p = ptr; struct autoload_data_i *p = ptr;
rb_gc_mark(p->feature); rb_gc_mark(p->feature);
rb_gc_mark(p->thread);
rb_gc_mark(p->value); rb_gc_mark(p->value);
} }
@ -1965,8 +1976,8 @@ rb_autoload(VALUE mod, ID id, const char *file)
ad = TypedData_Make_Struct(0, struct autoload_data_i, &autoload_data_i_type, ele); ad = TypedData_Make_Struct(0, struct autoload_data_i, &autoload_data_i_type, ele);
ele->feature = fn; ele->feature = fn;
ele->safe_level = rb_safe_level(); ele->safe_level = rb_safe_level();
ele->thread = Qnil;
ele->value = Qundef; ele->value = Qundef;
ele->state = 0;
st_insert(tbl, (st_data_t)id, (st_data_t)ad); st_insert(tbl, (st_data_t)id, (st_data_t)ad);
} }
@ -2039,7 +2050,7 @@ rb_autoloading_value(VALUE mod, ID id, VALUE* value)
if (!(load = autoload_data(mod, id)) || !(ele = check_autoload_data(load))) { if (!(load = autoload_data(mod, id)) || !(ele = check_autoload_data(load))) {
return 0; return 0;
} }
if (ele->thread == rb_thread_current()) { if (ele->state && ele->state->thread == rb_thread_current()) {
if (ele->value != Qundef) { if (ele->value != Qundef) {
if (value) { if (value) {
*value = ele->value; *value = ele->value;
@ -2079,16 +2090,6 @@ autoload_const_set(VALUE arg)
return 0; /* ignored */ return 0; /* ignored */
} }
/* this is on the thread stack, not heap */
struct autoload_state {
struct autoload_data_i *ele;
VALUE mod;
VALUE result;
ID id;
struct list_node waitq_node; /* links autoload_data_i.waitq_head */
VALUE waiting_th;
};
static VALUE static VALUE
autoload_require(VALUE arg) autoload_require(VALUE arg)
{ {
@ -2107,9 +2108,9 @@ autoload_reset(VALUE arg)
struct autoload_state *state = (struct autoload_state *)arg; struct autoload_state *state = (struct autoload_state *)arg;
int need_wakeups = 0; int need_wakeups = 0;
if (state->ele->thread == rb_thread_current()) { if (state->ele->state == state) {
need_wakeups = 1; need_wakeups = 1;
state->ele->thread = Qnil; state->ele->state = 0;
} }
/* At the last, move a value defined in autoload to constant table */ /* At the last, move a value defined in autoload to constant table */
@ -2130,11 +2131,11 @@ autoload_reset(VALUE arg)
if (need_wakeups) { if (need_wakeups) {
struct autoload_state *cur, *nxt; struct autoload_state *cur, *nxt;
list_for_each_safe(&state->ele->waitq_head, cur, nxt, waitq_node) { list_for_each_safe(&state->waitq.head, cur, nxt, waitq.node) {
VALUE th = cur->waiting_th; VALUE th = cur->thread;
cur->waiting_th = Qfalse; cur->thread = Qfalse;
list_del(&cur->waitq_node); list_del(&cur->waitq.node);
/* /*
* cur is stored on the stack of cur->waiting_th, * cur is stored on the stack of cur->waiting_th,
@ -2161,7 +2162,7 @@ rb_autoload_load(VALUE mod, ID id)
src = rb_sourcefile(); src = rb_sourcefile();
if (src && loading && strcmp(src, loading) == 0) return Qfalse; if (src && loading && strcmp(src, loading) == 0) return Qfalse;
/* set ele->thread for a marker of autoloading thread */ /* set ele->state for a marker of autoloading thread */
if (!(ele = check_autoload_data(load))) { if (!(ele = check_autoload_data(load))) {
return Qfalse; return Qfalse;
} }
@ -2169,25 +2170,25 @@ rb_autoload_load(VALUE mod, ID id)
state.ele = ele; state.ele = ele;
state.mod = mod; state.mod = mod;
state.id = id; state.id = id;
if (ele->thread == Qnil) { state.thread = rb_thread_current();
ele->thread = rb_thread_current(); if (!ele->state) {
ele->state = &state;
/* /*
* autoload_reset will wake up any threads added to this * autoload_reset will wake up any threads added to this
* iff the GVL is released during autoload_require * iff the GVL is released during autoload_require
*/ */
list_head_init(&ele->waitq_head); list_head_init(&state.waitq.head);
} }
else { else {
state.waiting_th = rb_thread_current(); list_add_tail(&ele->state->waitq.head, &state.waitq.node);
list_add_tail(&ele->waitq_head, &state.waitq_node);
/* /*
* autoload_reset in other thread will resume us and remove us * autoload_reset in other thread will resume us and remove us
* from the waitq list * from the waitq list
*/ */
do { do {
rb_thread_sleep_deadly(); rb_thread_sleep_deadly();
} while (state.waiting_th != Qfalse); } while (state.thread != Qfalse);
} }
/* autoload_data_i can be deleted by another thread while require */ /* autoload_data_i can be deleted by another thread while require */
@ -2594,8 +2595,8 @@ const_update(st_data_t *key, st_data_t *value, st_data_t arg, int existing)
load = autoload_data(klass, id); load = autoload_data(klass, id);
/* for autoloading thread, keep the defined value to autoloading storage */ /* for autoloading thread, keep the defined value to autoloading storage */
if (load && (ele = check_autoload_data(load)) && if (load && (ele = check_autoload_data(load)) && ele->state &&
(ele->thread == rb_thread_current())) { (ele->state->thread == rb_thread_current())) {
rb_clear_constant_cache(); rb_clear_constant_cache();
ele->value = val; /* autoload_i is non-WB-protected */ ele->value = val; /* autoload_i is non-WB-protected */