From: "David Hildenbrand (Arm)" <david@kernel.org>
To: Gregory Price <gourry@gourry.net>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
kernel-team@meta.com, akpm@linux-foundation.org, ljs@kernel.org,
liam@infradead.org, vbabka@kernel.org, rppt@kernel.org,
surenb@google.com, mhocko@suse.com, mingo@redhat.com,
peterz@infradead.org, juri.lelli@redhat.com,
vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de,
vschneid@redhat.com, kprateek.nayak@amd.com, ziy@nvidia.com,
baolin.wang@linux.alibaba.com, nico.pache@linux.dev,
ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org,
lance.yang@linux.dev, usama.arif@linux.dev, kas@kernel.org,
matthew.brost@intel.com, joshua.hahnjy@gmail.com,
rakie.kim@sk.com, byungchul@sk.com, ying.huang@linux.alibaba.com,
apopple@nvidia.com, jannh@google.com, pfalcato@suse.de,
osalvador@suse.de, hannes@cmpxchg.org, raghavendra.kt@amd.com,
stable@vger.kernel.org
Subject: Re: [PATCH v2 2/4] mm: allow shared folios to be promoted to a fast tier
Date: Fri, 18 Sep 2026 15:57:55 +0200 [thread overview]
Message-ID: <989e3584-4008-4c5b-a49f-ed84b656ed14@kernel.org> (raw)
In-Reply-To: <aq1A90ltg9Qn6pWZ@gourry-fedora-PF4VCD3F>
On 9/18/26 15:54, Gregory Price wrote:
> On Fri, Sep 18, 2026 at 02:53:40PM +0200, David Hildenbrand (Arm) wrote:
>> On 9/11/26 02:18, Gregory Price wrote:
>>> From: "Gregory Price (Meta)" <gourry@gourry.net>
>>>
>>> NUMA balancing rejects shared copy-on-write folios and executable
>>> file folios mapped by multiple processes to avoid placement bouncing.
>>> These checks also block promotion from slow memory.
>>
>> Right. How to we know the direction of promotion vs. demotion, though?
>>
>
> numa balancing never demotes. It either:
>
> 1) moves between sockets (nodes w/ N_CPU) (NORMAL)
> or
> 2) moves from !top_tier to top_tier (TIERING)
>
> Demotion is only enacted in reclaim / vmscan, and has no coupling with
> numa balancing.
>
Valuable to briefly mention that here, and have some helper functions that make
this obvious (and maybe document it as well ;) ) :)
--
Cheers,
David
next prev parent reply other threads:[~2026-09-18 13:58 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-11 0:18 [PATCH v2 0/4] sched/numa: stop VMA scan filters from gating promotion Gregory Price
2026-09-11 0:18 ` [PATCH v2 1/4] mm: support promotion-only NUMA hinting scans Gregory Price
2026-09-17 16:03 ` Peter Zijlstra
2026-09-17 16:14 ` Gregory Price
2026-09-18 12:26 ` David Hildenbrand (Arm)
2026-09-18 12:37 ` David Hildenbrand (Arm)
2026-09-18 13:46 ` Gregory Price
2026-09-18 13:56 ` David Hildenbrand (Arm)
2026-09-11 0:18 ` [PATCH v2 2/4] mm: allow shared folios to be promoted to a fast tier Gregory Price
2026-09-17 16:08 ` Peter Zijlstra
2026-09-17 16:18 ` Gregory Price
2026-09-17 16:23 ` Peter Zijlstra
2026-09-17 16:39 ` Gregory Price
2026-09-18 4:14 ` Bharata B Rao
2026-09-17 17:49 ` Zi Yan
2026-09-18 12:54 ` David Hildenbrand (Arm)
2026-09-18 12:53 ` David Hildenbrand (Arm)
2026-09-18 13:54 ` Gregory Price
2026-09-18 13:57 ` David Hildenbrand (Arm) [this message]
2026-09-11 0:18 ` [PATCH v2 3/4] sched/numa: scan read-only file mappings in tiering mode Gregory Price
2026-09-18 12:58 ` David Hildenbrand (Arm)
2026-09-18 13:57 ` Gregory Price
2026-09-18 13:59 ` David Hildenbrand (Arm)
2026-09-18 14:53 ` Lorenzo Stoakes (ARM)
2026-09-18 15:48 ` Gregory Price
2026-09-18 16:19 ` Lorenzo Stoakes (ARM)
2026-09-18 16:38 ` Gregory Price
2026-09-11 0:18 ` [PATCH v2 4/4] sched/numa: do not let VMA PID activity gate promotion Gregory Price
2026-09-17 16:19 ` Peter Zijlstra
2026-09-18 13:01 ` David Hildenbrand (Arm)
2026-09-18 13:59 ` Gregory Price
2026-09-11 5:38 ` [PATCH v2 0/4] sched/numa: stop VMA scan filters from gating promotion Gregory Price
2026-09-17 5:35 ` Andrew Morton
2026-09-17 6:59 ` Gregory Price
2026-09-17 15:53 ` David Hildenbrand (Arm)
2026-09-18 20:56 ` Zi Yan
2026-09-18 21:42 ` Gregory Price
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