mirror of
https://github.com/jart/cosmopolitan.git
synced 2025-02-07 06:53:33 +00:00
624573207e
This change doubles the performance of thread spawning. That's thanks to our new stack manager, which allows us to avoid zeroing stacks. It gives us 15µs spawns rather than 30µs spawns on Linux. Also, pthread_exit() is faster now, since it doesn't need to acquire the pthread GIL. On NetBSD, that helps us avoid allocating too many semaphores. Even if that happens we're now able to survive semaphores running out and even memory running out, when allocating *NSYNC waiter objects. I found a lot more rare bugs in the POSIX threads runtime that could cause things to crash, if you've got dozens of threads all spawning and joining dozens of threads. I want cosmo to be world class production worthy for 2025 so happy holidays all
88 lines
4.4 KiB
C
88 lines
4.4 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2023 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/intrin/ulock.h"
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#include "libc/calls/syscall_support-sysv.internal.h"
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#include "libc/errno.h"
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#include "libc/intrin/describeflags.h"
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#include "libc/intrin/kprintf.h"
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#include "libc/intrin/strace.h"
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#include "libc/intrin/ulock.h"
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// XNU futexes
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// https://opensource.apple.com/source/xnu/xnu-7195.50.7.100.1/bsd/sys/ulock.h.auto.html
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// https://opensource.apple.com/source/xnu/xnu-3789.41.3/bsd/kern/sys_ulock.c.auto.html
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int sys_ulock_wait(uint32_t operation, void *addr, uint64_t value,
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uint32_t timeout_micros) asm("sys_futex_cp");
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// returns number of other waiters, or -1 w/ errno
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//
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// - EINTR means a signal handler was called. This is how we support
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// things like POSIX thread cancelation.
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//
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// - EFAULT if XNU couldn't read `addr`. This is normally considered a
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// programming error, but with ulock it can actually be a transient
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// error due to low memory conditions. Apple recommends retrying.
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//
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// - ENOMEM means XNU wasn't able to allocate memory for kernel internal
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// data structures. Apple doesn't provide any advice on what to do. We
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// simply turn this into EAGAIN.
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//
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// - EAGAIN if XNU told us EFAULT but cosmo believes the address exists.
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// This value is also used as a substitute for ENOMEM.
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//
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// - EINVAL could mean operation is invalid, addr is null or misaligned;
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// it could also mean another thread calling ulock on this address was
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// configured (via operation) in an inconsistent way.
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//
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// see also os_sync_wait_on_address.h from xcode sdk
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int ulock_wait(uint32_t operation, void *addr, uint64_t value,
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uint32_t timeout_micros) {
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int rc;
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operation |= ULF_WAIT_CANCEL_POINT;
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LOCKTRACE("ulock_wait(%#x, %p, %lx, %u) → ...", operation, addr, value,
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timeout_micros);
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rc = sys_ulock_wait(operation, addr, value, timeout_micros);
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if (rc == -1) {
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if (errno == ENOMEM)
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errno = EAGAIN;
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if (errno == EFAULT)
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if (!kisdangerous(addr))
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errno = EAGAIN;
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}
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LOCKTRACE("ulock_wait(%#x, %p, %lx, %u) → %d% m", operation, addr, value,
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timeout_micros, rc);
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return rc;
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}
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// returns -errno
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//
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// - ENOENT means there wasn't anyone to wake
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//
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// - EINVAL could mean operation is invalid, addr is null or misaligned;
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// it could also mean another thread calling ulock on this address was
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// configured (via operation) in an inconsistent way.
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//
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int ulock_wake(uint32_t operation, void *addr, uint64_t wake_value) {
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int rc;
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rc = __syscall3i(operation, (long)addr, wake_value, 0x2000000 | 516);
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LOCKTRACE("ulock_wake(%#x, %p, %lx) → %s", operation, addr, wake_value,
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DescribeErrno(rc));
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return rc;
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}
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