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

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Date:   Mon, 15 Apr 2019 15:10:00 -0700
From:   Yang Shi <yang.shi@...ux.alibaba.com>
To:     Dave Hansen <dave.hansen@...el.com>, mhocko@...e.com,
        mgorman@...hsingularity.net, riel@...riel.com, hannes@...xchg.org,
        akpm@...ux-foundation.org, keith.busch@...el.com,
        dan.j.williams@...el.com, fengguang.wu@...el.com, fan.du@...el.com,
        ying.huang@...el.com, ziy@...dia.com
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [v2 PATCH 5/9] mm: vmscan: demote anon DRAM pages to PMEM node



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.

Thanks,
Yang