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Date: Mon, 10 Dec 2007 17:43:58 +0800
From: "Xiao-Feng Li" <xiaofeng.li@gmail.com>
To: dev@harmony.apache.org
Subject: Re: [drlvm][general] Multi-tasking VM?
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On Dec 10, 2007 5:02 PM, Simon Chow <simon.harmony@gmail.com> wrote:
> Yes, I agree that.
>
> But I think MVM's feature of sharing class runtime representations across
> applications' can make many apps benefit not only at startup phases, but
> also at runtime.

Yes. Runtime sharing could be useful. Without MVM, this can be made
available through OS supports to dynamic shared objects (with careful
design).

> Besides these, I guess processes scheduling may be useful when running 2
> related programs like server and database.
> And migration Java processes between defferent JVMs would be useful for load
> balance and reliability in distributed enviroment.

I remember MVM was only for shared memory system, no support to
distributed environment (unless you meant distributed shared memory
system, but that's too far a concept). Btw, please use the word
"process" carefully, because the tasks in MVM are not the processes in
traditional sense. My understanding of "process" is clearly the entity
with address space isolation.

> Ok, it may be useless idea in practice. But if all these things can be
> achived just by MVM. Is it valuable to do it?

The problem is, whether we want to achieve those benefits with MVM if
they can attained through other approaches. In my opinion, the key
concept of MVM is to share the same virtual address space between
multiple JVM instances. But since the address space isolation with
process has been well established, proven, and mature in current
platforms, then how to share the space needs deep thinking and serious
proving.

Simon, it's good for you to think of these things. It's always
encouraged. And my comments are only my personal opinions, just for
your reference.

Thanks,
xiaofeng

> Thanks for your comments!
>
>
> On 10/12/2007, Xiao-Feng Li < xiaofeng.li@gmail.com> wrote:
> >
> > On Dec 10, 2007 2:49 PM, Simon Chow <simon.harmony@gmail.com> wrote:
> > > Acturally, I am just a greenhand for JVM.
> > > After seeing some paper about MVM, which says MVM can reduce the startup
> >
> > > overhead and footprint of programs, I think both destop application and
> > > server application can benefit from it.
> > > In my opinion, at least, some IDE can use it for debugging small program
> > > more conveniently by avoiding startup overhead.
> > >
> > > Could you say something about its shortage?
> > > Thank you!
> >
> > Simon, I think the advantage (shorter startup time) of MVM you
> > mentioned can be achieved without MVM. Don't you think so?
> >
> > Thanks,
> > xiaofeng
> > >
> > > On 10/12/2007, Xiao-Feng Li <xiaofeng.li@gmail.com> wrote:
> > > >
> > > > On Dec 10, 2007 1:00 PM, Simon Chow < simon.harmony@gmail.com> wrote:
> > > > > Will harmony support the multi-tasking feature?
> > > > > I has seen that Sun has a project name
> > > > > Barcelona< http://research.sun.com/projects/barcelona>which aimed to
> > > > > run several Java applications on 1 JVM.
> > > > > Maybe it can improve the JVM performance somehow.
> > > > > I am very interested about this, but I can not find more resource
> > about
> > > > > this....
> > > >
> > > > In foreseeable future, Harmony might have no plan for MVM support. I
> > > > had some investigations in this area, and I personally am not fully
> > > > convinced by the idea.
> > > >
> > > > Thanks,
> > > > xiaofeng
> > > >
> > > > > --
> > > > > From : Simon.Chow@Software School of Fudan University
> > > > >
> > > >
> > > >
> > > >
> > > > --
> > > > http://xiao-feng.blogspot.com
> > > >
> > >
> > >
> > >
> > > --
> > >
> > > From : Simon.Chow@Software School of Fudan University
> > >
> >
> >
> >
> > --
> > http://xiao-feng.blogspot.com
> >
>
>
>
> --
>
> From : Simon.Chow@Software School of Fudan University
>


-- 
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