On Tue, Mar 11, 2025 at 10:53:41AM -0400, Zi Yan wrote: > On 20 Feb 2025, at 14:26, David Hildenbrand wrote: > > > Yes, the only way to get some 1 GiB pages is by using larger memory blocks (e.g., 2 GiB on x86-64), which comes with a different set of issues (esp. hotplug granularity). > > An alternative I can think of is to mark a hot-plugged memory block dedicated > to memmap and use it for new memory block’s memmap provision. In this way, > a 256MB memory block can be used for 256MB*(256MB/4MB)=16GB hot plugged memory. > Yes, it will waste memory before 256MB+16GB is online, but that might be > easier to handle than variable sized memory block, I suppose? > > > The devil is in the details here. We'd need a way for the driver to tell hotplug "use this for memmap for some yet-to-be-mapped region" - rather than having that allocate naturally. Either this, or a special ZONE specifically for memmap allocations. ~Gregory
