[squeak-dev] 64 bit images

Colin Putney cputney at wiresong.ca
Tue Nov 17 02:33:05 UTC 2009


On 16-Nov-09, at 2:40 PM, Eliot Miranda wrote:

> One was Quallaby.  They did a network monitoring app that had huge  
> numbers of large integers in a graph representing the state of the  
> network.

I worked on that app for bit. We had one installation we had to be  
careful with because the images were 3.5 GB, and if we got beyond  
that, there wasn't enough room for the VM to work. Other customers  
were smaller but headed upwards and we could see that we would hit the  
limit eventually. At that point we were already processing much more  
than 4GB of data at once, but the partitioning into separate images  
was based on external factors and wasn't very flexible. Before I left,  
I was part of a project to move to a more cloudy architecture where  
partitioning was much more flexible.

I guess the take-away from that was that many cooperating smaller  
images works as well or better than one huge image. There might be  
applications where that's not true, and everything *has* to be in the  
same address space, but I can't think of any.

That is not to say, however, that 64-bit images aren't needed, just  
that images larger than 4 GB are the least interesting implication of  
having 64-bit pointers. I'd rather use the pointer bandwidth for more/ 
better immediate values, and run in 64-bit mode for better use of the  
hardware and integration with the host OS.

Colin



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