On Wed, May 08, 2024 at 04:44:32PM +0100, Pavel Begunkov wrote: > > like a weird and indirect way to get there. Why can't io_uring just be > > the entity that does the final free and not mess with the logic > > allocator? > > Then the user has to do a syscall (e.g. via io_uring) to return pages, > and there we'd need to care how to put the pages efficiently, i.e. > hitting the page pool's fast path, e.g. by hoping napi is scheduled and > scheduled for the CPU we're running on, or maybe transferring the pages > to the right CPU first. > > Compare it with userspace putting pages into a ring, and the allocator > taking from there when needed without any extra synchronisation and > hassle just because it's a sole consumer. Wow, that sounds a bit terrifying for security, but I guess I can see your point. You are replacing the whole allocator logic if you are effectively putting the free list in userspace memory. Jason
