Hello , please review this small test fix .
The test test/jdk/sun/management/HotspotRuntimeMBean/GetTotalSafepointTime.java
fails sometimes on fast Linux machines with this error message :
java.lang.RuntimeException: Total safepoint time illegal value: 0 ms (MIN = 1;
MAX = 9223372036854775807)
looks like the total safepoint time is too low currently on these machines, it
is < 1 ms.
There might be several ways to handle this :
* Change the test in a way that it might generate nigher safepoint times
* Allow safepoint time == 0 ms
* Offer an additional interface that gives safepoint times with finer
granularity ( currently the HS has safepoint time values in ns , see
jdk/src/hotspot/share/runtime/safepoint.cpp SafepointTracing::end
But it is converted on ms in this code
114jlong RuntimeService::safepoint_time_ms() {
115 return UsePerfData ?
116 Management::ticks_to_ms(_safepoint_time_ticks->get_value()) : -1;
117}
064jlong Management::ticks_to_ms(jlong ticks) {
2065 assert(os::elapsed_frequency() > 0, "Must be non-zero");
2066 return (jlong)(((double)ticks / (double)os::elapsed_frequency())
2067 * (double)1000.0);
2068}
Currently I go for the first attempt (and try to generate higher safepoint
times in my patch) .
Bug/webrev :
https://bugs.openjdk.java.net/browse/JDK-8228658
http://cr.openjdk.java.net/~mbaesken/webrevs/8228658.0/
Thanks, Matthias
