Combining client and server VM

[Krystal Mok]

Hi Stefan,

On what version of JDK are you testing with? Oracle JDK/OpenJDK doesn't
ship a 64-bit Client VM.

Tiered-compilation is only available in the Server VM (which is actually a
Tiered VM now). The Server VM has both the Client Compiler (C1) and Server
Compiler (C2), and in tiered-mode both compilers are active; where as the
Client VM only has C1.

So, turning on -XX:+TieredCompilation with -client doesn't really make
sense.

- Kris


On Fri, Jan 24, 2014 at 2:35 PM, Stefan Reich <
stefan.reich.maker.of.eye at googlemail.com> wrote:

> Hi David!
>
> Thanks, that was actually new to me even though I'm an avid Java fan.
>
> It does help a bit:
>
> -client
>
> ImageToLua.convert: 170 ms
> real    0m4.763s
> user    0m1.452s
> sys    0m0.124s
>
> -server
>
> ImageToLua.convert: 1108 ms
> real    0m12.597s
> user    0m7.008s
> sys    0m0.388s
>
> -client -XX:+TieredCompilation
>
> ImageToLua.convert: 181 ms
> real    0m5.686s
> user    0m1.488s
> sys    0m0.144s
>
> -server -XX:+TieredCompilation
>
> ImageToLua.convert: 398 ms
> real    0m8.827s
> user    0m4.572s
> sys    0m0.256s
>
> This is a run of a short program (as you can see), so we're testing
> start-up time and probably only first-level compilations.
> ImageToLua.convert is one of the calculating functions.
>
> So TieredCompilation is indeed faster in startup than the pure server VM.
> It still is quite a bit slower than -client, so I'm still lusting for a
> perfect solution (start-up performance on part with client VM).
>
> Cheers :)
> Stefan
>
>
>
> On Fri, Jan 24, 2014 at 9:49 PM, David Schlosnagle <schlosna at gmail.com
> >wrote:
>
> > Sounds like you're describing -XX:+TieredCompilation [1], already
> > available in HotSpot.
> >
> > [1]:
> >
> http://docs.oracle.com/javase/7/docs/technotes/guides/vm/performance-enhancements-7.html#tieredcompilation
> >
> >
> > On Fri, Jan 24, 2014 at 3:29 PM, Stefan Reich <
> > stefan.reich.maker.of.eye at googlemail.com> wrote:
> >
> >> Hi there!
> >>
> >> Is this the official HotSpot list? Looks like it.
> >>
> >> I am Stefan. Here's my short bio: I was an early HotSpot adopter (before
> >> its release) and now I reinvent programming (www.TinyBrain.de).
> >>
> >> OK, on to the topic: I'd LOVE to see the HotSpot client and server VMs
> >> combined into one engine. A combination seems to me like pretty much the
> >> ideal VM to have.
> >>
> >> It would basically start as the client VM in order to get stuff started
> >> quickly, least delays possible.
> >>
> >> When initialisations are done, after a few seconds or so, the VM
> switches
> >> to server mode, delivering highly-optimized code.
> >>
> >> I need to restart VMs a lot, but I still want maximum performance, for
> >> example for GUIs. It's OK to have a slower GUI for a few seconds if
> you're
> >> rewarded with full speed shortly after that.
> >>
> >> Is it possible? Shouldn't be too hard to implement, right? Anyone up for
> >> it?
> >>
> >> Cheers,
> >> Stefan
> >>
> >> --
> >>
> >> Stefan Reich
> >> TinyBrain.de
> >> We will beat Google to A.I.
> >>
> >
> >
>