On 7/27/23 2:53 PM, Michal Hocko wrote:
> On Thu 27-07-23 13:32:29, Aneesh Kumar K.V wrote:
> [...]
>> + if (mode == MEMMAP_ON_MEMORY_FORCE) {
>> + unsigned long memmap_pages =
>> memory_block_memmap_on_memory_pages();
>> +
>> + pr_info_once("Memory hotplug will reserve %ld pages in each
>> memory block\n",
>> + memmap_pages - PFN_UP(memory_block_memmap_size()));
>> + }
>> + return 0;
>> +}
>
> Why should we print this only for the forced case? Isn't that
> interesting for any on memory memmap? Also is this the above sufficient
> on its own? the size depends on the block size and that can vary.
> I think it would make more sense to print the block size and the vmemmap
> reservation and for the force case also any wasted amount on top (if
> any).
>
For the other cases the space is completely used by for struct page allocation.
What
the information is indicating here is that for each memblock we add we are
loosing/wasting so many pages.
May be I should have used the term "waste" instead of "reserve" ?
-aneesh
