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 < mechanical-sympathy@googlegroups.com> 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 mechanical-sympathy+unsubscr...@googlegroups.com. > 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 mechanical-sympathy+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
