cosmopolitan/third_party/nsync/testing/cv2_test.c
Justine Tunney 2f48a02b44
Make recursive mutexes faster
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
2024-09-10 00:08:59 -07:00

24 lines
1.9 KiB
C

/*-*- mode:c;indent-tabs-mode:t;c-basic-offset:8;tab-width:8;coding:utf-8 -*-│
│ vi: set noet ft=c ts=8 sw=8 fenc=utf-8 :vi │
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│ Copyright 2016 Google Inc. │
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│ Licensed under the Apache License, Version 2.0 (the "License"); │
│ you may not use this file except in compliance with the License. │
│ You may obtain a copy of the License at │
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│ http://www.apache.org/licenses/LICENSE-2.0 │
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│ Unless required by applicable law or agreed to in writing, software │
│ distributed under the License is distributed on an "AS IS" BASIS, │
│ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. │
│ See the License for the specific language governing permissions and │
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╚─────────────────────────────────────────────────────────────────────────────*/
#include "third_party/nsync/testing/cv_test.inc"
int main (int argc, char *argv[]) {
testing_base tb = testing_new (argc, argv, 0);
TEST_RUN (tb, test_cv_deadline);
return (testing_base_exit (tb));
}