[PATCH] A steadier steady_clock

[Sam Varshavchik]

Based on a casual browsing of clock_gettime(3), CLOCK_MONOTONIC_RAW seems to be a better fit for std::chrono::steady_clock's requirements as given in 20.11.7.2, with recent Linux kernels,

Something like this:

Index: libstdc++-v3/src/c++11/chrono.cc
===================================================================
--- libstdc++-v3/src/c++11/chrono.cc    (revision 192652)
+++ libstdc++-v3/src/c++11/chrono.cc    (working copy)
@@ -70,7 +70,11 @@
    {
      timespec tp;
      // -EINVAL, -EFAULT
+#ifdef CLOCK_MONOTONIC_RAW
+      clock_gettime(CLOCK_MONOTONIC_RAW, &tp);
+#else
      clock_gettime(CLOCK_MONOTONIC, &tp);
+#endif
      return time_point(duration(chrono::seconds(tp.tv_sec)
                                 + chrono::nanoseconds(tp.tv_nsec)));
    }

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