Hi Daniel,
Thanks for the review on the API side, and for the detailed
consideration of any potential spec issues - of which they are none I'm
glad to say.
Cheers,
David
On 27/05/2020 1:35 am, Daniel Fuchs wrote:
Hi David,
This is not a review for the posix code.
Your webrev looks good to me and corresponds to what I expected
to see. I understand that not all operating systems / platforms
are expected to have the nano second precision, so your test
probably can't go much beyond what is currently being tested.
Last time I upgraded the system clock to micro second precision [1]
I had to write a CSR and release notes. That was the first time
the clock went beyond millisecond precision however - and my
expectation is that your proposed change should no longer
require a CSR as potential nanosecond precision should
now be covered by the spec.
I had to modify a few other places as well (see [1]) - where precision
greater than 1ms was not expected, but these modifications
should cover your current changes too, so I don't think anything
more is required. Some --test-repeat might be in order
to verify things are stable but I don't expect any issue there :-)
LGTM.
best regards,
-- daniel
[1] https://bugs.openjdk.java.net/browse/JDK-8068730
On 26/05/2020 05:59, David Holmes 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
