linux-kernel - Re: [PATCH v2 0/2] Add a new scheme to support demotion on tiered memory system

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <362fb4fe-34c8-d83d-b8be-a4140e19b244@linux.alibaba.com>
Date:   Thu, 23 Dec 2021 09:01:05 +0800
From:   Baolin Wang <baolin.wang@...ux.alibaba.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     sj@...nel.org, ying.huang@...el.com, dave.hansen@...ux.intel.com,
        ziy@...dia.com, shy828301@...il.com,
        zhongjiang-ali@...ux.alibaba.com, xlpang@...ux.alibaba.com,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 0/2] Add a new scheme to support demotion on tiered
 memory system



On 12/23/2021 8:01 AM, Andrew Morton wrote:
> On Wed, 22 Dec 2021 19:14:39 +0800 Baolin Wang <baolin.wang@...ux.alibaba.com> wrote:
> 
>> Now on tiered memory system with different memory types, the reclaim path in
>> shrink_page_list() already support demoting pages to slow memory node instead
>> of discarding the pages. However, at that time the fast memory node memory
>> wartermark is already tense, which will increase the memory allocation latency
>> during page demotion. So a new method from user space demoting cold pages
>> proactively will be more helpful.
>>
>> We can rely on the DAMON in user space to help to monitor the cold memory on
>> fast memory node, and demote the cold pages to slow memory node proactively to
>> keep the fast memory node in a healthy state.
>>
>> This patch set introduces a new scheme named DAMOS_DEMOTE to support this feature,
>> and works well from my testing. Any comments are welcome. Thanks.
> 
> This is interesting.
> 
> I think it would be helpful if we could have some example scenarios in
> this changelog, help people understand how to use DAMOS_DEMOTE and what
> effects it has.

Sure.

> 
> Documentation/admin-guide/mm/damon/usage.rst would like an update?

Ah, I missed updating de Doc, and will do in v3.

> And the DAMON user space tool?

Yes. Thanks for your comments.