If the kernel implementation of clock_gettime is correct, copying the implementation in the vDSO into the JVM should be okay too, right? If rdtsc was not stable, it should have the same problems if invoked from either place?
On Monday, April 29, 2019 at 10:50:05 PM UTC-7, dor laor wrote: > > It might be since in the past many systems did not have a stable rdtsc and > thus if the instruction is executed > on different sockets it can result in wrong answers and negative time. > Today most systems do have a stable tsc > and you can verify it from userspace/java too. > I bet it's easy to google the reason > > On Mon, Apr 29, 2019 at 2:36 PM 'Carl Mastrangelo' via mechanical-sympathy > <[email protected] <javascript:>> wrote: > >> This may be a dumb question, but why (on Linux) is System.nanotime() a >> call out to clock_gettime? It seems like it could be inlined by the JVM, >> and stripped down to the rdtsc instruction. From my reading of the vDSO >> source for x86, the implementation is not that complex, and could be copied >> into Java. >> >> -- >> You received this message because you are subscribed to the Google Groups >> "mechanical-sympathy" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected] <javascript:>. >> For more options, visit https://groups.google.com/d/optout. >> > -- You received this message because you are subscribed to the Google Groups "mechanical-sympathy" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
