On Feb 21, 2008, at 5:35 PM, Stephen Pair wrote:

> I must say, this is a really impressive development.  I really think  
> this is the right way to approach multi-core systems.
>
> At work, we have a highly distributed system (some customers are  
> running as many as 50 nodes with a mix of VW and C++ processes on  
> each).  Occassionally some of our people in the field or customers  
> complain that any one process isn't taking advantage of the multi- 
> core architectures they run on.  After reminding them that in fact  
> we are using those CPUs because we are running many processes on  
> those nodes, we also highlight the fact that our C++ component,  
> which utilizes many threads (in a retrospectively naive way),  
> actually degrades in performance when you drop it onto a multi-core  
> machine (and it degrades badly).  All those highly active threads  
> contending for the same shared memory isn't quite so good.  ;)

Could you elaborate on the shared-memory contention? Last year we were  
having the preliminary discussions that led to Hydra VM, and I argued  
(on theoretical grounds) that  fine-grained multithreading within a  
single object memory could cause serious memory contention problems.   
I'd be interested to hear more about your real-world experiences.

Thanks,
Josh


>
> - Stephen
>
> On Thu, Feb 21, 2008 at 8:22 PM, Igor Stasenko <siguctua at gmail.com>  
> wrote:
> On 22/02/2008, Andreas Raab <andreas.raab at gmx.de> wrote:
> > Stephen Pair wrote:
> >  > How does one start a second image (or does it do this  
> automatically
> >  > based on the number of cores)?
> >
> >
> > Load the HydraVM package and execute:
> >
> >    HydraVM saveAsHeadlessImage: 'core.image'
> >
> >  This will save the current image in a form ready for loading it  
> in the
> >  background. When you've saved it, start it via:
> >
> >    HydraVM loadAndRunNewImage: 'core.image'
> >
> >
> >  > On my machine, it seems to run ok for about a minute or so and  
> then
> >  > freeze up (this is on a Windows XP core duo machine).
> >
> >
> > Interesting. Others have mentioned the same effect. I'm using a  
> slightly
> >  older version of the VM which seems a little more stable (but I  
> know
> >  Igor is looking into the problem).
> >
>
> This was introduced due to my latest changes. Sorry guys i didn't  
> meant that. :)
> I had freezing problems on my own PC, and did some fixes to eliminate
> that before releasing an update. As it turned out, something in
> environment (Windows?) causing VM to freeze, because i tested same
> images and with same VM binaries and it worked just fine on my PC.
>
>
> >  Cheers,
> >
> >    - Andreas
> >
> >
>
>
> --
> Best regards,
> Igor Stasenko AKA sig.
>
>
>

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