[squeak-dev] A pretty big Squeak 4.3 image (nearly 8 GB)

David T. Lewis lewis at mail.msen.com
Sat Jan 14 20:48:09 UTC 2012

On Sat, Jan 14, 2012 at 05:18:23PM +0100, Bert Freudenberg wrote:
> On 14.01.2012, at 17:09, David T. Lewis wrote:
> > Here is a screen shot of the Squeak 4.3 release image traced to 64-bit
> > object format, showing the image size after allocating a lot of object
> > memory. This is running on a box with 8GB of real memory, so the image
> > is about as large as can get on my computer.
> > 
> > <http://squeakvm.org/~lewis/squeak4.3-64bit/squeak64-big.png>
> Yay!
> > The image is fully functional and can be saved to disk and reloaded.
> > Monticello and other tools all work, and the image can be updated from
> > the trunk update stream as normal. Saving the image to disk and restarting
> > it are slow due the file size and amount of memory used, but the image
> > itself works fine. Garbage collection works, and overall the performance
> > remains good up to the point that the operating system is forced to start
> > page swapping (because the image is larger than available real memory
> > on this box).
> > 
> > Dave
> For reducing startup time, it might be a good idea to use the mmap trick
> of suggesting a target address. That way no oop adjustment is necessary
> on startup because the object memory would likely have the same base address.
> Pages are loaded on demand, so it would take until the first full GC to
> load the whole image into memory. IIRC, John got that to work on iOS.

It's times like this that I really appreciate the Mantis bug tracker. The
background on John's mmap approach is recorded here:


Along with a link to the original discussions on vm-dev:


And the related updates that were added to VMMaker in VMMaker-dtl.109.

... just in case anyone else is trying to keep track of this.


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