On Tue, May 06, 2025 at 09:52:22AM -0300, Jason Gunthorpe wrote: > On Mon, May 05, 2025 at 12:50:56PM -0700, Nicolin Chen wrote: > > > I wanted to ask: what should we pass in to the "entry"? An mmap > > structure that hold the pfn range? Or just pfn_start? > > Some kind of struct telling you what is behind that pfn range so you > can invoke the right driver callback and retun the right pfns..
I see. > > With that being said, it seems that I have been misusing the > > mtree data structure, treating it as an xarray. In your very > > first email suggesting the mmap design, where you mentioned > > "xarray" first and "maple tree" following. So, I thought they > > can be used in the similar way, especially after reading this: > > https://lwn.net/Articles/846175/ > > This job requires a range based datastructure. Meaning you insert PFNs > A->B and then a lookup would search for any intersection with A->B. > > In maple tree you can do this rather directly since it is inherently > range based. > > In xarray you can do it with the multi-order feature or you can do it > by replicating the entry across the whole range. So, if I understand it correctly, what we want to achieve is to have maple tree to manage all PFN ranges. And each range holds the same entry, a structure that we can use to verify the sanity of an mmap? Let's say for PFNs A->B, the tree should store the structure between index A and index B (inclusive)? If this is correct, mtree_alloc_range() that is given a range of [0, ULONG_MAX] would allocate the PFN range from the lowest index (i.e. 0) instead of PFN A? Thanks Nicolin
