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From:   "Huang, Ying" <ying.huang@intel.com>
To:     Jianlin Lv <iecedge@gmail.com>
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Subject: Re: [PATCH] memcg: add interface to force disable swap
References: <20231007130905.78554-1-jianlv@ebay.com>
        <87mswtkj8x.fsf@yhuang6-desk2.ccr.corp.intel.com>
        <CAFA-uR9ymPTktMbi96cb+smjQHB4Y=8SQfAqmsqTbniGbkGTLA@mail.gmail.com>
Date:   Sun, 08 Oct 2023 16:24:02 +0800
In-Reply-To: <CAFA-uR9ymPTktMbi96cb+smjQHB4Y=8SQfAqmsqTbniGbkGTLA@mail.gmail.com>
        (Jianlin Lv's message of "Sun, 8 Oct 2023 15:52:04 +0800")
Message-ID: <87il7hjzdp.fsf@yhuang6-desk2.ccr.corp.intel.com>
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Jianlin Lv <iecedge@gmail.com> writes:

> On Sun, Oct 8, 2023 at 9:17=E2=80=AFAM Huang, Ying <ying.huang@intel.com>=
 wrote:
>>
>> Jianlin Lv <iecedge@gmail.com> writes:
>>
>> > From: Jianlin Lv <iecedge@gmail.com>
>> >
>> > Global reclaim will swap even if swappiness is set to 0.
>>
>> Why?  Can you elaborate the situation?
>
> We reproduced the issue of pages being swapped out even when swappiness is
> set to 0 in the production environment through the following test program.
> Not sure whether this program can reproduce the issue in any environment.
>
> From the implementation of the get_scan_count code, it can be seen that,
> based on the current runtime situation, memory reclamation will choose a
> scanning method (SCAN_ANON/SCAN_FILE/SCAN_FRACT) to determine how
> aggressively the anon and file LRU are scanned. However, this introduces
> uncertainty.
>
> For the JVM issue at hand, we expect deterministic SCAN_FILE scan to avoid
> swapping out anon pages.

Why doesn't memory.swap.max work?

--
Best Regards,
Huang, Ying