The JIT for example uses polling to sample the state. It sets a timer to pop in a few ms and goes to sleep. But since that state change and timer interrupt reflection isn't in hardware the cost appears excessive. If you would be computing pi second level in Linux it may still be pretty decent. And because the optimizer uses elapsed time rather than cpu time it keeps recompiling classes and kind of digs is own grave. You might try without the optimizer on 2nd level Linux. This is probably too specialist topic for general consumption. We can have the discussion offline next week when I'm online again :-) On Apr 17, 2015 8:36 AM, "Pavelka, Tomas" <[email protected]> wrote:
> Hi Rob, > thanks for the reply. The performance of Linux under a second level VM > always seemed unpredictable to me but after reading your response I started > seeing a pattern: whenever I had a poorly performing application on Linux > on a second level VM, there was always some kind of networking involved > which in turn involved waiting on open sockets. > I just want to ensure I am understanding correctly what your are saying: > Is it true that waits under software SIE burn CPU where the same waits > under hardware SIE do not? That would explain a lot of the performance > problems I have seen but I am sure there are caveats. > > Thanks, > Tomas > > ---------------------------------------------------------------------- > For LINUX-390 subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO LINUX-390 or > visit > http://www.marist.edu/htbin/wlvindex?LINUX-390 > ---------------------------------------------------------------------- > For more information on Linux on System z, visit > http://wiki.linuxvm.org/ > ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 ---------------------------------------------------------------------- For more information on Linux on System z, visit http://wiki.linuxvm.org/
