linux-kernel - Re: [PATCH v9 0/5] ksm: support tracking KSM-placed zero-pages

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Date:   Wed, 24 May 2023 11:12:28 +0200
From:   David Hildenbrand <david@...hat.com>
To:     yang.yang29@....com.cn, akpm@...ux-foundation.org
Cc:     imbrenda@...ux.ibm.com, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, ran.xiaokai@....com.cn, xu.xin.sc@...il.com,
        xu.xin16@....com.cn, jiang.xuexin@....com.cn
Subject: Re: [PATCH v9 0/5] ksm: support tracking KSM-placed zero-pages

On 24.05.23 07:51, yang.yang29@....com.cn wrote:
> From: xu xin <xu.xin16@....com.cn>
> 
> The core idea of this patch set is to enable users to perceive the number
> of any pages merged by KSM, regardless of whether use_zero_page switch has
> been turned on, so that users can know how much free memory increase is
> really due to their madvise(MERGEABLE) actions. But the problem is, when
> enabling use_zero_pages, all empty pages will be merged with kernel zero
> pages instead of with each other as use_zero_pages is disabled, and then
> these zero-pages are no longer monitored by KSM.
> 
> The motivations to do this is seen at:
> https://lore.kernel.org/lkml/202302100915227721315@zte.com.cn/
> 
> In one word, we hope to implement the support for KSM-placed zero pages
> tracking without affecting the feature of use_zero_pages, so that app
> developer can also benefit from knowing the actual KSM profit by getting
> KSM-placed zero pages to optimize applications eventually when
> /sys/kernel/mm/ksm/use_zero_pages is enabled.
> 


Ran the tests and they worked as expected. I only had some remaining 
feedback for the last patch, otherwise LGTM.

-- 
Thanks,

David / dhildenb