|Posted by David|
in reply to Imperatorn
Posted in reply to Imperatorn
On Wednesday, 24 February 2021 at 06:14:58 UTC, Imperatorn wrote:
> On Tuesday, 23 February 2021 at 19:44:39 UTC, David wrote:
>> Not sure if `learn` is the right topic or not to post this..
>> I've been going through Bob Nystrom's "Crafting Interpreters" for a bit of fun and over the weekend put together a toy allocator in D - free and gc not yet done. It's single threaded and unsurprisingly faster than malloc for small objects up to 512 bytes, and about the same for larger objects (simulated with a linear distribution of size requests).
> Have you looked at the "experimental" allocator(s) in D?
Hi, yes, good question, yes I did - my first cut using the mmap_allocator was slower - I presume because I should really allocate a good chunk of virtual memory and manage the pages myself.
So some questions I'm asking myself -
What people's heuristics for switching methods say from, some sort of pool to another approach - e.g. linked list of pages? At the page level does a bitmap allocator make more sense?
Knuth (it seems) was under the impression that a third of memory is wasted by fragmentation, aka the 50% rule - that doesn't seem likely, does anyone measure these things?
How does one go about choosing a set of pool sizes?
Given that virtual pages are not necessarily physically contiguous are some of the considerations that inspired the buddy system no longer relevant.
I should also say I'm aiming for a single thread longish running process (one + working days) that I anticipate could use a good chunk say 100GB or so on occasion but I'd like to be more efficient than java in terms of memory reuse - past experience was I had to reboot my workstation a few times a day as it did something really horrible (I don't know what).
Any there any GC frameworks that someone has shared in D?