RFR(S): 8231457 Asserts on AIX because os::elapsed_counter() is not monotonic

[David Holmes]

Hi Arno,

On 26/09/2019 8:37 pm, Zeller, Arno wrote:
> Hi,
> 
> we have seen assertions on AIX 7.2 on Power9 that complain about negative durations. The issue seems to be caused by the implementation of o::elapsed_counter() on AIX that uses gettimeofday which is not monotonic. To solve the issue I prepared a small patch that let os::elapsed_counter() use javaTimeNanos() which should be monotonic. I had to adjust also os::elapsed_frequency() and os::elapsedTime() to be consistent.
> 
> Bug: https://bugs.openjdk.java.net/browse/JDK-8231457
> Webrev: http://cr.openjdk.java.net/~azeller/webrevs/8231457_2/
> 
> I will need a sponsor for this patch.

Changes looks good. I will sponsor this for you. Will wait for a second 
reviewer.

Thanks,
David


> Best regards,
> Arno
>