linux-kernel - Re: [PATCH v8 3/3] mm/mempolicy: Support memory hotplug in weighted interleave

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Message-ID: <680038591bb93_1302d29427@dwillia2-xfh.jf.intel.com.notmuch>
Date: Wed, 16 Apr 2025 16:08:09 -0700
From: Dan Williams <dan.j.williams@...el.com>
To: Rakie Kim <rakie.kim@...com>, <akpm@...ux-foundation.org>
CC: <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>,
	<david@...hat.com>, <Jonathan.Cameron@...wei.com>, <osalvador@...e.de>,
	<kernel_team@...ynix.com>, <honggyu.kim@...com>, <yunjeong.mun@...com>,
	<rakie.kim@...com>
Subject: Re: [PATCH v8 3/3] mm/mempolicy: Support memory hotplug in weighted
 interleave

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.
> 
> Co-developed-by: Honggyu Kim <honggyu.kim@...com>
> Signed-off-by: Honggyu Kim <honggyu.kim@...com>
> Co-developed-by: Yunjeong Mun <yunjeong.mun@...com>
> Signed-off-by: Yunjeong Mun <yunjeong.mun@...com>
> Signed-off-by: Rakie Kim <rakie.kim@...com>
> Reviewed-by: Oscar Salvador <osalvador@...e.de>
> Reviewed-by: Joshua Hahn <joshua.hahnjy@...il.com>
> Reviewed-by: Gregory Price <gourry@...rry.net>
> Acked-by: David Hildenbrand <david@...hat.com>

Looks good.

Reviewed-by: Dan Williams <dan.j.williams@...el.com>