linux-kernel - Re: [PATCH v7 3/3] mm/mempolicy: Support memory hotplug in weighted interleave

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Message-ID: <b58f2dd6-d978-487a-b420-badfb4847c00@sk.com>
Date: Wed, 9 Apr 2025 20:39:47 +0900
From: Honggyu Kim <honggyu.kim@...com>
To: David Hildenbrand <david@...hat.com>, Rakie Kim <rakie.kim@...com>,
 akpm@...ux-foundation.org
Cc: kernel_team@...ynix.com, gourry@...rry.net, linux-mm@...ck.org,
 linux-kernel@...r.kernel.org, linux-cxl@...r.kernel.org,
 joshua.hahnjy@...il.com, dan.j.williams@...el.com,
 ying.huang@...ux.alibaba.com, Jonathan.Cameron@...wei.com,
 osalvador@...e.de, yunjeong.mun@...com
Subject: Re: [PATCH v7 3/3] mm/mempolicy: Support memory hotplug in weighted
 interleave

Hi David,

On 4/9/2025 6:05 PM, David Hildenbrand wrote:
> On 08.04.25 09:32, Rakie Kim wrote:
>> The weighted interleave policy distributes page allocations across multiple
>> NUMA nodes based on their performance weight, thereby improving memory
>> bandwidth utilization. The weight values for each node are configured
>> through sysfs.
>>
>> Previously, sysfs entries for configuring weighted interleave were created
>> for all possible nodes (N_POSSIBLE) at initialization, including nodes that
>> might not have memory. However, not all nodes in N_POSSIBLE are usable at
>> runtime, as some may remain memoryless or offline.
>> This led to sysfs entries being created for unusable nodes, causing
>> potential misconfiguration issues.
>>
>> To address this issue, this patch modifies the sysfs creation logic to:
>> 1) Limit sysfs entries to nodes that are online and have memory, avoiding
>>     the creation of sysfs entries for nodes that cannot be used.
>> 2) Support memory hotplug by dynamically adding and removing sysfs entries
>>     based on whether a node transitions into or out of the N_MEMORY state.
>>
>> Additionally, the patch ensures that sysfs attributes are properly managed
>> when nodes go offline, preventing stale or redundant entries from persisting
>> in the system.
>>
>> By making these changes, the weighted interleave policy now manages its
>> sysfs entries more efficiently, ensuring that only relevant nodes are
>> considered for interleaving, and dynamically adapting to memory hotplug
>> events.
>>
>> Signed-off-by: Rakie Kim <rakie.kim@...com>
>> Signed-off-by: Honggyu Kim <honggyu.kim@...com>
>> Signed-off-by: Yunjeong Mun <yunjeong.mun@...com>
> 
> 
> Why are the other SOF in there? Are there Co-developed-by missing?

I initially found the problem and fixed it with my internal implementation but
Rakie also had his idea so he started working on it.  His initial implementation
has almost been similar to mine.

I thought Signed-off-by is a way to express the patch series contains our
contribution, but if you think it's unusual, then I can add this.

   Co-developed-by: Honggyu Kim <honggyu.kim@...com>
   Signed-off-by: Honggyu Kim <honggyu.kim@...com>

For Yunjeong, the following can be added.

   Tested-by: Yunjeong Mun <yunjeong.mun@...com>

However, this patch series is already in Andrew's mm-new so I don't want to
bother him again unless we need to update this patches for other reasons.

Is this okay?

Thanks,
Honggyu

> 
> 
> Acked-by: David Hildenbrand <david@...hat.com>
>