D GC theory

[Kagamin via Digitalmars-d]

On Tuesday, 24 February 2015 at 00:30:43 UTC, ketmar wrote:
> On Mon, 23 Feb 2015 21:11:22 +0000, Sativa wrote:
>
>> How hard would it be to modify D's GC to do the following two 
>> things:
>> 
>> 1. Scan the heap in the BG on another thread/cpu for 
>> compactification.
>
> needs read/write barriers added to generated code. a major 
> slowdown for
> ALL memory access.

Only modifications of pointers, which introduce new cross-block 
dependencies (so that GC knows to recheck the new dependency). 
Other memory access goes without slowdown.