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Introduce pthread_condattr_setclock()

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This is one of the few POSIX APIs that was missing. It lets you choose a
monotonic clock for your condition variables. This might improve perf on
some platforms. It might also grant more flexibility with NTP configs. I
know Qt is one project that believes it needs this. To introduce this, I
needed to change some the *NSYNC APIs, to support passing a clock param.
There's also new benchmarks, demonstrating Cosmopolitan's supremacy over
many libc implementations when it comes to mutex performance. Cygwin has
an alarmingly bad pthread_mutex_t implementation. It is so bad that they
would have been significantly better off if they'd used naive spinlocks.
This commit is contained in:
Justine Tunney 2024-09-02 23:37:50 -07:00
parent 79516bf08e
commit 3c61a541bd
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GPG key ID: BE714B4575D6E328
55 changed files with 449 additions and 155 deletions
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libc/thread/pthread_barrier_wait.c
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@ -61,7 +61,7 @@ errno_t pthread_barrier_wait(pthread_barrier_t *barrier) {
// wait for everyone else to arrive at barrier
BLOCK_CANCELATION;
while ((n = atomic_load_explicit(&barrier->_waiters, memory_order_acquire)))
nsync_futex_wait_(&barrier->_waiters, n, barrier->_pshared, 0);
nsync_futex_wait_(&barrier->_waiters, n, barrier->_pshared, 0, 0);
ALLOW_CANCELATION;
return 0;