Ruby の GVL をなくすと遅くなる

bench.rb

GC.disable

def sieve_of_eratosthenes(limit)
  is_prime = Array.new(limit + 1, true)
  is_prime[0] = is_prime[1] = false # 0 と 1 は素数ではない

  (2..Math.sqrt(limit)).each do |i|
    if is_prime[i]
      (i * i..limit).step(i) do |j|
        is_prime[j] = false
      end
    end
  end

  is_prime.each_with_index.map { |prime, index| index if prime }.compact
end

ths = []

10.times do
  ths << Thread.new {
    sieve_of_eratosthenes(1000000)
  }
end

ths.each(&:join)

nogvl.diff

diff --git a/thread.c b/thread.c
index 2a937ca278..684efea3bc 100644
--- a/thread.c
+++ b/thread.c
@@ -1445,6 +1445,7 @@ rb_thread_sleep(int sec)
 static void
 rb_thread_schedule_limits(uint32_t limits_us)
 {
+    return;
     if (!rb_thread_alone()) {
         rb_thread_t *th = GET_THREAD();
         RUBY_DEBUG_LOG("us:%u", (unsigned int)limits_us);
diff --git a/thread_pthread.c b/thread_pthread.c
index c92fd52a66..8f39530581 100644
--- a/thread_pthread.c
+++ b/thread_pthread.c
@@ -384,6 +384,8 @@ ractor_sched_dump_(const char *file, int line, rb_vm_t *vm)
 static void
 thread_sched_lock_(struct rb_thread_sched *sched, rb_thread_t *th, const char *file, int line)
 {
+    // printf("lo: th:%p\n", th);
+    return;
     rb_native_mutex_lock(&sched->lock_);

 #if VM_CHECK_MODE
@@ -398,6 +400,8 @@ thread_sched_lock_(struct rb_thread_sched *sched, rb_thread_t *th, const char *f
 static void
 thread_sched_unlock_(struct rb_thread_sched *sched, rb_thread_t *th, const char *file, int line)
 {
+    // printf("un: th:%p\n", th);
+    return;
     RUBY_DEBUG_LOG2(file, line, "th:%u", rb_th_serial(th));

 #if VM_CHECK_MODE

run

% time /home/osyoyu/.rbenv/versions/master/bin/ruby ~/Development/bench.rb
/home/osyoyu/.rbenv/versions/master/bin/ruby ~/Development/bench.rb  0.99s user 0.07s system 99% cpu 1.058 total

% time ./miniruby ~/Development/bench.rb
./miniruby ~/Development/bench.rb  17.68s user 0.11s system 904% cpu 1.969 total