[PATCH] D38481: Use sched_getaffinity instead of std::thread::hardware_concurrency when available

[Rui Ueyama via Phabricator via llvm-commits]

ruiu added inline comments.


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Comment at: include/llvm/Support/ThreadPool.h:42
+  /// Construct a pool with the number of threads found by
+  /// get_available_threads().
   ThreadPool();
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hardware_concurrency()


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Comment at: lib/Support/Threading.cpp:82
+#endif
+  return std::thread::hardware_concurrency();
+}
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AFAIK std::thread::hardware_concurrency() is allowed to return 0 if it doesn't know anything about hardware concurrency. I don't know if there's actually such system that the function could return 0, but it is better to not rely on an undefined behavior. I'd explicitly check if std::thread::hardware_concurrency returns 0 and if that's the case, return 1.


https://reviews.llvm.org/D38481