linux-kernel - Re: [PATCH] mm: migrate: Do not retry 10 times for the subpages of fail-to-migrate THP

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Date:   Mon, 1 Aug 2022 10:33:41 +0800
From:   Baolin Wang <baolin.wang@...ux.alibaba.com>
To:     "Huang, Ying" <ying.huang@...el.com>
Cc:     akpm@...ux-foundation.org, ziy@...dia.com, shy828301@...il.com,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm: migrate: Do not retry 10 times for the subpages of
 fail-to-migrate THP



On 7/28/2022 2:16 PM, Huang, Ying wrote:
> Hi, Baolin,
> 
> Baolin Wang <baolin.wang@...ux.alibaba.com> writes:
> 
>> If THP is failed to migrate due to -ENOSYS or -ENOMEM case, the THP will
>> be split, and the subpages of fail-to-migrate THP will be tried to migrate
>> again, so we should not account the retry counter in the second loop, since
>> we already accounted 'nr_thp_failed' in the first loop.
>>
>> Moreover we also do not need retry 10 times for -EAGAIN case for the subpages
>> of fail-to-migrate THP in the second loop, since we already regarded the
>> THP as migration failure, and save some migration time (for the worst case,
>> will try 512 * 10 times) according to previous discussion [1].
>>
>> [1] https://lore.kernel.org/linux-mm/87r13a7n04.fsf@yhuang6-desk2.ccr.corp.intel.com/
>>
>> Signed-off-by: Baolin Wang <baolin.wang@...ux.alibaba.com>
> 
> I have tested this patch, and it works as expected.
> 
> Tested-by: "Huang, Ying" <ying.huang@...el.com>

Thanks.

> 
>> ---
>> Note, this patch is based on the patch set [1] from Huang Ying.
>> [1] https://lore.kernel.org/linux-mm/20220711084948.274787-1-ying.huang@intel.com/
> 
> Please this patch is based on my patchset that hasn't been merged.  I
> can add it as the last patch of my migrate_pages failure path fixing
> patchset if you don't object.

Sure, please fold it into your series. Thanks for helping.