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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=989e3584-4008-4c5b-a49f-ed84b656ed14@kernel.org \
--to=david@kernel.org \
--cc=akpm@linux-foundation.org \
--cc=apopple@nvidia.com \
--cc=baohua@kernel.org \
--cc=baolin.wang@linux.alibaba.com \
--cc=bsegall@google.com \
--cc=byungchul@sk.com \
--cc=dev.jain@arm.com \
--cc=dietmar.eggemann@arm.com \
--cc=gourry@gourry.net \
--cc=hannes@cmpxchg.org \
--cc=jannh@google.com \
--cc=joshua.hahnjy@gmail.com \
--cc=juri.lelli@redhat.com \
--cc=kas@kernel.org \
--cc=kernel-team@meta.com \
--cc=kprateek.nayak@amd.com \
--cc=lance.yang@linux.dev \
--cc=liam@infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=ljs@kernel.org \
--cc=matthew.brost@intel.com \
--cc=mgorman@suse.de \
--cc=mhocko@suse.com \
--cc=mingo@redhat.com \
--cc=nico.pache@linux.dev \
--cc=osalvador@suse.de \
--cc=peterz@infradead.org \
--cc=pfalcato@suse.de \
--cc=raghavendra.kt@amd.com \
--cc=rakie.kim@sk.com \
--cc=rostedt@goodmis.org \
--cc=rppt@kernel.org \
--cc=ryan.roberts@arm.com \
--cc=stable@vger.kernel.org \
--cc=surenb@google.com \
--cc=usama.arif@linux.dev \
--cc=vbabka@kernel.org \
--cc=vincent.guittot@linaro.org \
--cc=vschneid@redhat.com \
--cc=ying.huang@linux.alibaba.com \
--cc=ziy@nvidia.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.