low-latency GC

[Ola Fosheim Grostad]

On Sunday, 6 December 2020 at 17:35:19 UTC, IGotD- wrote:
> Is automatic atomic reference counting a contender for kernels? 
> In kernels you want to reduce the increase/decrease of the 
> counts. Therefore the Rust approach using 'clone' is better 
> unless there is some optimizer that can figure it out. 
> Performance is important in kernels, you don't want the kernel 
> to steal useful CPU time that otherwise should go to programs.

I am not sure if kernel authors want autmatic memory management, 
they tend to want full control and transparency. Maybe something 
people who write device drivers would consider.

> In general I think that reference counting should be supported 
> in D, not only implicitly but also under the hood with fat 
> pointers. This will make D more attractive to performance 
> applications. Another advantage is the reference counting can 
> use malloc/free directly if needed without any complicated GC 
> layer with associated meta data.

Yes, I would like to see it, just expect that there will be 
protests when people realize that they have to make ownership 
explicit.

> Also tracing GC in a kernel is my opinion not desirable. For 
> the reason I previously mentioned, you want to reduce meta 
> data, you want reduce CPU time, you want to reduce 
> fragmentation. Special allocators for structures are often used.

Yes, an ARC solution should support fixed size allocators for 
types that are frequently allocated to get better speed.