Combining client and server VM

[Stefan Reich]

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.
>> >>
>> >
>> >
>>
>
>