Jeremie Pelletier, el 13 de septiembre a las 22:58 me escribiste: > 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
I saw a paper about that. The idea was to simply have some list of objects/pages in each generation and modify that lists instead of moving objects. I can't remember the name of the paper so I can't find it now :S The problem with generational collectors (in D) is that you need read/write barriers to track inter-generational pointers (to be able to use pointers to younger generations in the older ones as roots when scanning), which can make the whole deal a little unpractical for a language that doesn't want to impose performance penalty to thing you wont use (I don't see a way to instrument read/writes to pointers to the GC only). This is why RC was always rejected as an algorithm for the GC in D, I think. > 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 :) -- Leandro Lucarella (luca) | Blog colectivo: http://www.mazziblog.com.ar/blog/ ---------------------------------------------------------------------------- GPG Key: 5F5A8D05 (F8CD F9A7 BF00 5431 4145 104C 949E BFB6 5F5A 8D05) ---------------------------------------------------------------------------- Pack and get dressed before your father hears us, before all hell breaks loose.
