[Vm-dev] [OpenSmalltalk/opensmalltalk-vm] Store key Spur GC parameters in image header (#477)

[David T. Lewis]

On Thu, Feb 20, 2020 at 09:51:04AM -0800, tim Rowledge wrote:
>  
> Just to be completist (and possibly completely ridiculous) I'll mention an alternative option;
> - store the desired values in the image
> - make it possible to change the assorted zone sizes at runtime
> 
> I totally understand that the work to do that may be absurd verging into
> DaDa. The (faintly) plausible advantage would be runtime tuning as a
> system grows, allowing adaptive strategies etc, etc, {insert buzzword here}
> 
> > On 2020-02-20, at 8:14 AM, Eliot Miranda <notifications at github.com> wrote:
> > 
> > It would be convenient if the Spur headroom growth size, shrinking
> ratio, and heap growth ratio for full GCs/old space were stored in the
> image header as ???desired??? values, alongside new space, code zone, and
> stack zone sizes.
> 

All of these schemes are inherently unmaintainable over time and across
any non-trivial mix of VMs and images.

The solution is simple: Don't do that.

We have a perfectly good mechanism for supporting optional interactions
with the VM. Named primitives are designed to do this. They work very
well, with no need for (human) management oversight. A primitive either
works or it doesn't, and if it doesn't work then fine, the VM does not
support whatever you were trying to tell it to do. Simple, easy, bulletproof,
and no management oversight required.

Dave