On Fri, 12 Jan 2018 13:34:05 -0500 Pavel Tatashin <pasha.tatas...@oracle.com> wrote:
> Deferred page initialization allows the boot cpu to initialize a small > subset of the system's pages early in boot, with other cpus doing the rest > later on. > > It is, however, problematic to know how many pages the kernel needs during > boot. Different modules and kernel parameters may change the requirement, > so the boot cpu either initializes too many pages or runs out of memory. > > To fix that, initialize early pages on demand. This ensures the kernel > does the minimum amount of work to initialize pages during boot and leaves > the rest to be divided in the multithreaded initialization path > (deferred_init_memmap). > > The on-demand code is permanently disabled using static branching once > deferred pages are initialized. After the static branch is changed to > false, the overhead is up-to two branch-always instructions if the zone > watermark check fails or if rmqueue fails. Presumably this fixes some real-world problem which someone has observed? Please describe that problem for us in lavish detail.
