Re: [PATCH 06/10] mm: vmscan: demote anon DRAM pages to PMEM node

[Dave Hansen]

On 3/27/19 10:00 AM, Zi Yan wrote:
> I ask this because I observe that migrating a list of pages can
> achieve higher throughput compared to migrating individual page.
> For example, migrating 512 4KB pages can achieve ~750MB/s
> throughput, whereas migrating one 4KB page might only achieve
> ~40MB/s throughput. The experiments were done on a two-socket
> machine with two Xeon E5-2650 v3 @ 2.30GHz across the QPI link.

What kind of migration?

If you're talking about doing sys_migrate_pages() one page at a time,
that's a world away from doing something inside of the kernel one page
at a time.