Re: [v2 PATCH 5/9] mm: vmscan: demote anon DRAM pages to PMEM node

From: Yang Shi
Date: Mon Apr 15 2019 - 18:10:14 EST

On 4/11/19 7:31 AM, Dave Hansen wrote:
On 4/10/19 8:56 PM, Yang Shi wrote:
include/linux/gfp.h | 12 ++++
include/linux/migrate.h | 1 +
include/trace/events/migrate.h | 3 +-
mm/debug.c | 1 +
mm/internal.h | 13 +++++
mm/migrate.c | 15 ++++-
mm/vmscan.c | 127 +++++++++++++++++++++++++++++++++++------
7 files changed, 149 insertions(+), 23 deletions(-)
Yikes, that's a lot of code.

And it only handles anonymous pages?

Yes, for the time being. But, it is easy to extend to all kind of pages.

Also, I don't see anything in the code tying this to strictly demote
from DRAM to PMEM. Is that the end effect, or is it really implemented
that way and I missed it?

No, not restrict to PMEM. It just tries to demote from "preferred node" (or called compute node) to a memory-only node. In the hardware with PMEM, PMEM would be the memory-only node.