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thread_pthread.c: reset timeslice delay when uncontended

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This matches the behavior of old timer thread more closely
and seems to fix [Bug #14999] when limited to a single CPU.
I cannot reproduce the error on a multi-core system unless
I use schedtool to force affinity to a single CPU:

schedtool -a 0x01 -e make test-spec \
	MSPECOPT='-R1000 spec/ruby/library/conditionvariable/wait_spec.rb'

While it may be good enough to pass the spec, I don't have
huge degree of confidence in the interrupt handling robustness
under extremely heavy load (these may be ancient bugs, though).

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@64467 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
This commit is contained in:
normal 2018-08-19 00:01:08 +00:00
parent 77038f9f82
commit d2afeb9445
2 changed files with 7 additions and 3 deletions
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9
thread_pthread.c
View File

@ -180,19 +180,18 @@ static void
do_gvl_timer(rb_vm_t *vm, rb_thread_t *th)
{
static struct timespec ts;
static int err = ETIMEDOUT;
native_thread_data_t *nd = &th->native_thread_data;
/* take over wakeups from UBF_TIMER */
ubf_timer_disarm();
if (err == ETIMEDOUT) {
if (vm->gvl.timer_err == ETIMEDOUT) {
ts.tv_sec = 0;
ts.tv_nsec = TIME_QUANTUM_NSEC;
ts = native_cond_timeout(&nd->cond.gvlq, ts);
}
vm->gvl.timer = th;
err = native_cond_timedwait(&nd->cond.gvlq, &vm->gvl.lock, &ts);
vm->gvl.timer_err = native_cond_timedwait(&nd->cond.gvlq, &vm->gvl.lock, &ts);
vm->gvl.timer = 0;
ubf_wakeup_all_threads();
@ -244,6 +243,9 @@ gvl_acquire_common(rb_vm_t *vm, rb_thread_t *th)
rb_native_cond_signal(&vm->gvl.switch_cond);
}
}
else { /* reset timer if uncontended */
vm->gvl.timer_err = ETIMEDOUT;
}
vm->gvl.acquired = th;
if (!vm->gvl.timer) {
if (!designate_timer_thread(vm) && !ubf_threads_empty()) {
@ -325,6 +327,7 @@ gvl_init(rb_vm_t *vm)
list_head_init(&vm->gvl.waitq);
vm->gvl.acquired = 0;
vm->gvl.timer = 0;
vm->gvl.timer_err = ETIMEDOUT;
vm->gvl.need_yield = 0;
vm->gvl.wait_yield = 0;
}

1
thread_pthread.h
View File

@ -53,6 +53,7 @@ typedef struct rb_global_vm_lock_struct {
/* slow path */
struct list_head waitq;
const struct rb_thread_struct *timer;
int timer_err;
/* yield */
rb_nativethread_cond_t switch_cond;