Combining client and server VM (original) (raw)

Stefan Reich stefan.reich.maker.of.eye at googlemail.com
Fri Jan 24 15:36:55 PST 2014

Java version:

java version "1.6.0_27" OpenJDK Runtime Environment (IcedTea6 1.12.6) (6b27-1.12.6-1ubuntu0.12.04.4) OpenJDK Client VM (build 20.0-b12, mixed mode, sharing)

It's all 32 bit.

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

Yup, I figured as much. Included that only to see what the switch does in both modes.

Stefan

On Sat, Jan 25, 2014 at 12:00 AM, Krystal Mok <rednaxelafx at gmail.com> wrote:

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. >> > >

More information about the hotspot-dev mailing list