[erlang-questions] 64-bit erlang

[Lev Walkin]

How do you provide heap segmentation so a single heap stays within a 
contiguous piece of memory? Are there any memory fragmentation 
considerations?


Ulf Wiger (TN/EAB) wrote:
> We've had reason to start discussing 64-bit Erlang, and
> I thought I'd share some thoughts, hoping that others will
> share theirs.
> 
> In one application, we're starting to hit the 4 GB ceiling,
> and we're discussing ways to address the situation. One
> option is to install more RAM, but then we need to either
> run multiple nodes on each machine (affects software
> complexity), or switch to 64-bit Erlang.
> 
> But 64-bit Erlang consumes up to twice as much memory as
> 32-bit Erlang, so if we switch to more expensive RAM and
> install 8 GB, worst case, we'll still have roughly the
> same capacity. The cost per GB goes up, which cuts into
> the per-unit profit margin.
> 
> After this, we'd be able to sail into the sunset on 64-bit
> Erlang, installing more and more gigabytes of RAM.  (:
> But the entry threshold /is/ a bit high.
> 
> Here's an idea to get the discussion going:
> 
> How about using 32-bit words inside the process heap, and
> "far pointers" to any off-heap data (including other
> processes)?
> 
> After all, I doubt that anyone is seriously looking at having
> process heaps larger than 4 GB...
> 
> 
> BR,
> Ulf W
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