Hi, On Thu, Aug 20, 2020 at 09:07:29AM +0100, Ezequiel Garcia wrote: > > For single-device allocations, would using the buffer allocation > > functionality of that device's native API be better in most > > cases? (Some other possibly relevant discussion at [1]) > > > > That may be true for existing subsystems. > > However, how about a new subsystem/API wanting to > leverage the heap API and avoid exposing yet another > allocator API? > > And then, also, if we have an allocator API, perhaps > we could imagine a future where applications would only > need to worry about that, and not about each per-framework > allocator. Yeah both are reasonable points. I was thinking in the context of the thread I linked where allocating lots of GEM handles for process-local use is preferable to importing loads of dma_buf fds, but in that case the userspace graphics driver is somewhat "special" rather than a generic application in the traditional sense. I do think the best usage model for applications though is to use libraries which can hide the details, instead of going at the kernel APIs directly. > > > I can see that this can save some boilerplate for devices that want > > to expose private chunks of memory, but might it also lead to 100 > > aliases for the system's generic coherent memory pool? > > > > The idea (even if PoC) was to let drivers decide if they are special > enough to add themselves (via dev_dma_heap_add). OK, that makes sense. I think it's tricky to know how many "special" chunks of memory will already be hooked up to the DMA infrastructure and how many would need some extra/special work. Cheers, -Brian
