mirror of
https://github.com/jart/cosmopolitan.git
synced 2025-02-07 06:53:33 +00:00
2f48a02b44
Recursive mutexes now go as fast as normal mutexes. The tradeoff is they are no longer safe to use in signal handlers. However you can still have signal safe mutexes if you set your mutex to both recursive and pshared. You can also make functions that use recursive mutexes signal safe using sigprocmask to ensure recursion doesn't happen due to any signal handler The impact of this change is that, on Windows, many functions which edit the file descriptor table rely on recursive mutexes, e.g. open(). If you develop your app so it uses pread() and pwrite() then your app should go very fast when performing a heavily multithreaded and contended workload For example, when scaling to 40+ cores, *NSYNC mutexes can go as much as 1000x faster (in CPU time) than the naive recursive lock implementation. Now recursive will use *NSYNC under the hood when it's possible to do so
62 lines
3 KiB
C
62 lines
3 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
|
|
│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
|
|
╞══════════════════════════════════════════════════════════════════════════════╡
|
|
│ Copyright 2023 Justine Alexandra Roberts Tunney │
|
|
│ │
|
|
│ Permission to use, copy, modify, and/or distribute this software for │
|
|
│ any purpose with or without fee is hereby granted, provided that the │
|
|
│ above copyright notice and this permission notice appear in all copies. │
|
|
│ │
|
|
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
|
|
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
|
|
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
|
|
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
|
|
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
|
|
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
|
|
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
|
|
│ PERFORMANCE OF THIS SOFTWARE. │
|
|
╚─────────────────────────────────────────────────────────────────────────────*/
|
|
#include <assert.h>
|
|
#include <stdio.h>
|
|
#include <time.h>
|
|
|
|
#define MAXIMUM 1e9
|
|
#define ITERATIONS 10
|
|
|
|
const char *MyDescribeClockName(int clock) {
|
|
if (clock == CLOCK_REALTIME)
|
|
return "CLOCK_REALTIME";
|
|
if (clock == CLOCK_MONOTONIC)
|
|
return "CLOCK_MONOTONIC";
|
|
if (clock == CLOCK_REALTIME_COARSE)
|
|
return "CLOCK_REALTIME_COARSE";
|
|
if (clock == CLOCK_MONOTONIC_COARSE)
|
|
return "CLOCK_MONOTONIC_COARSE";
|
|
__builtin_trap();
|
|
}
|
|
|
|
void TestSleepRelative(int clock) {
|
|
printf("\n");
|
|
printf("testing: clock_nanosleep(%s) with relative timeout\n",
|
|
MyDescribeClockName(clock));
|
|
for (long nanos = 1; nanos < (long)MAXIMUM; nanos *= 2) {
|
|
struct timespec t1, t2, wf;
|
|
wf = timespec_fromnanos(nanos);
|
|
if (clock_gettime(clock, &t1))
|
|
return;
|
|
for (int i = 0; i < ITERATIONS; ++i) {
|
|
assert(!clock_nanosleep(clock, 0, &wf, 0));
|
|
}
|
|
clock_gettime(clock, &t2);
|
|
long took = timespec_tonanos(timespec_sub(t2, t1)) / ITERATIONS;
|
|
printf("%,12ld ns sleep took %,12ld ns delta %,12ld ns\n", nanos, took,
|
|
took - nanos);
|
|
}
|
|
}
|
|
|
|
int main(int argc, char *argv[]) {
|
|
TestSleepRelative(CLOCK_REALTIME);
|
|
TestSleepRelative(CLOCK_MONOTONIC);
|
|
TestSleepRelative(CLOCK_REALTIME_COARSE);
|
|
TestSleepRelative(CLOCK_MONOTONIC_COARSE);
|
|
}
|