AFAICT a nanosecond clock is fine from a java.time.* API perspective. Stephen
On Tue, 26 May 2020 at 06:01, David Holmes <david.hol...@oracle.com> wrote: > > bug: https://bugs.openjdk.java.net/browse/JDK-8242504 > webrev: http://cr.openjdk.java.net/~dholmes/8242504/webrev/ > > This work was contributed by Mark Kralj-Taylor: > > https://mail.openjdk.java.net/pipermail/hotspot-runtime-dev/2020-April/038975.html > > On the hotspot side we change the Linux implementations of > javaTimeMillis() and javaTimeSystemUTC() so that they use > clock_gettime(CLOCK_REALTIME) instead of gettimeofday(). In keeping with > our conditional use of this API I added a new guard > > os::Posix::supports_clock_gettime() > > and refined the existing supports_monotonic_clock() so that we can still > use CLOCK_REALTIME if CLOCK_MONOTONIC does not exist. In the future > (hopefully very near future) we will simply assume these APIs always exist. > > On the core-libs side the existing test: > > test/jdk/java/time/test/java/time/TestClock_System.java > > is adjusted to track the precision in more detail. > > Finally Mark has added instantNowAsEpochNanos() to the benchmark > previously known as > > test/micro/org/openjdk/bench/java/lang/Systems.java > > which I've renamed to SystemTime.java as Mark suggested. I agree having > these three functions measured together makes sense. > > Testing: > - test/jdk/java/time/test/java/time/TestClock_System.java > - test/micro/org/openjdk/bench/java/lang/SystemTime.java > - Tiers 1-3 > > Thanks, > David
