Deferred struct_page init can same more boot time, especially for large
memory instance. In my local test with 2C312GB VM, it decreases from
2.389s to 0.138s.
Please note that this has a potential performance impact on processes
running early in the lifetime of the system until these kthreads finish
the initialisation.
Signed-off-by: NShile Zhang <shile.zhang@linux.alibaba.com>
Acked-by: NJoseph Qi <joseph.qi@linux.alibaba.com>