Template Metaprogramming Made Easy (Huh?)

[Jeremie Pelletier]

Tom S Wrote:

> Jeremie Pelletier wrote:
> > Tom S Wrote:
> > 
> >> Jeremie Pelletier wrote:
> >>> I myself allocate all my meshes and textures directly on the GC and I'm pretty sure its faster than C's malloc and much safer.
> >> Hm, why would it be faster with the GC than malloc? I'm pretty sure it's 
> >> the opposite :P Plus, I could use a specialized malloc implementation, 
> >> like TLSF.
> > 
> > The D GC is already specialized, and given its being used quite a lot in D, there are good chances its already sitting in the CPU cache, its heap already having the available memory block waiting on a freelist, or if the alloc is more than 0x1000 bytes, the pages available in a pool. You'd need to use malloc quite a lot to get the same optimal performance, and mixing the two would affect the performance of both.
> 
> It might be specialized for _something_, but it definitely isn't 
> real-time systems. I'd say with my use cases there's a very poor chance 
> the GC is sitting in the CPU cache since most of the time my memory is 
> preallocated and managed by specialized structures and/or malloc. I've 
> found that using the GC only for the hard-to-manually-manage objects 
> works best. The rest is handled by malloc and the GC has a very shallow 
> vision of the world thus its collection runs are very fast. Of course 
> there's a drawback that both the GC and malloc will have some pages 
> cached, wasting memory, but I don't let the GC touch too much so it 
> should be minimal. YMMV of course - all depends on the memory allocation 
> patterns of the application.

I understand your points for using a separate memory manager, and I agree with you that having less active allocations make for faster sweeps, no matter how little of them are scanned for pointers. However I just had an idea on how to implement generational collection on a non-moving GC which should solve your issues (and well, mines too) with the collector not being fast enough. I need to do some hacking on my custom GC first, but I believe it could give yet another performance boost. I'll add my memory manager to my list of code modules to make public :)