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https://github.com/jart/cosmopolitan.git
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994e1f4386
Since we're now on Windows 8, we can have clone() work as advertised on Windows, where it sends a futex wake to the child tid. It's also likely we no longer need to work around thread flakes on OpenBSD, in _wait0().
87 lines
3.6 KiB
C
87 lines
3.6 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2022 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/atomic.h"
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#include "libc/calls/calls.h"
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#include "libc/calls/struct/timespec.h"
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#include "libc/intrin/intrin.h"
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#include "libc/mem/gc.h"
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#include "libc/mem/mem.h"
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#include "libc/stdio/stdio.h"
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#include "libc/testlib/testlib.h"
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#include "libc/thread/thread.h"
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#include "libc/time/time.h"
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/**
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* @fileoverview Lock Waiter Scalability Test
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*
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* This test can be run as follows:
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*
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* make o//test/libc/intrin/lockscale_test.com.runs V=5 TESTARGS=-b
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*
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* It's intended to demonstrate the importance of futexes. On systems
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* that don't have them, this test consumes orders of a magnitude more
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* cpu time, because there's a lot of waiters and they need to wait a
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* very long time.
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*/
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#define WAITERS 100
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#define ITERATIONS 10000
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atomic_int x;
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pthread_t t[WAITERS];
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pthread_mutex_t lock;
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pthread_barrier_t barrier;
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void Worker(void) {
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pthread_mutex_lock(&lock);
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pthread_barrier_wait(&barrier);
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for (x = 0; x < ITERATIONS; ++x) {
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sched_yield();
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}
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pthread_mutex_unlock(&lock);
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}
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void *Waiter(void *arg) {
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pthread_barrier_wait(&barrier);
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pthread_mutex_lock(&lock);
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ASSERT_EQ(ITERATIONS, x);
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pthread_mutex_unlock(&lock);
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return 0;
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}
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BENCH(lock, scalability) {
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int i;
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struct timespec t1, t2;
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t1 = _timespec_real();
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pthread_mutex_init(&lock, 0);
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pthread_barrier_init(&barrier, 0, WAITERS + 1);
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for (i = 0; i < WAITERS; ++i) {
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ASSERT_EQ(0, pthread_create(t + i, 0, Waiter, 0));
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}
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Worker();
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for (i = 0; i < WAITERS; ++i) {
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ASSERT_EQ(0, pthread_join(t[i], 0));
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}
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pthread_barrier_destroy(&barrier);
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pthread_mutex_destroy(&lock);
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t2 = _timespec_real();
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printf("consumed %10g seconds real time and %10g seconds cpu time\n",
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_timespec_tonanos(_timespec_sub(t2, t1)) / 1e9,
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(double)clock() / CLOCKS_PER_SEC);
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}
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