On 7/11/23 10:49 PM, David Hildenbrand wrote: > On 11.07.23 06:48, Aneesh Kumar K.V wrote: >> Add a new kconfig option that can be selected if we want to allow >> pageblock alignment by reserving pages in the vmemmap altmap area. >> This implies we will be reserving some pages for every memoryblock >> This also allows the memmap on memory feature to be widely useful >> with different memory block size values. > > "reserving pages" is a nice way of saying "wasting memory". :) Let's spell that out. > > I think we have to find a better name for this, and I think we should have a toggle similar to memory_hotplug.memmap_on_memory. This should be an admin decision, not some kernel config option. > > > memory_hotplug.force_memmap_on_memory > > "Enable the memmap on memory feature even if it could result in memory waste due to memmap size limitations. For example, if the memmap for a memory block requires 1 MiB, but the pageblock size is 2 MiB, 1 MiB > of hotplugged memory will be wasted. Note that there are still cases where the feature cannot be enforced: for example, if the memmap is smaller than a single page, or if the architecture does not support the forced mode in all configurations." > > Thoughts? > With module parameter, do we still need the Kconfig option? -aneesh
