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From: Davidlohr Bueso <dave@stgolabs.net>
To: Dave Hansen <dave.hansen@intel.com>
Cc: linux-mm@kvack.org, mhocko@kernel.org, akpm@linux-foundation.org,
	rientjes@google.com, yosryahmed@google.com, hannes@cmpxchg.org,
	shakeelb@google.com, dave.hansen@linux.intel.com,
	tim.c.chen@linux.intel.com, roman.gushchin@linux.dev,
	gthelen@google.com, a.manzanares@samsung.com,
	heekwon.p@samsung.com, gim.jongmin@samsung.com,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 6/6] mm/migrate: export whether or not node is toptier in sysf
Date: Mon, 18 Apr 2022 09:45:03 -0700	[thread overview]
Message-ID: <20220418164503.jfips3aiwhnlfjrq@offworld> (raw)
In-Reply-To: <c1475d8e-3ad6-cdab-5cc9-b44fef998636@intel.com>

On Mon, 18 Apr 2022, Dave Hansen wrote:

>On 4/16/22 20:49, Davidlohr Bueso wrote:
>> This allows userspace to know if the node is considered fast
>> memory (with CPUs attached to it). While this can be already
>> derived without a new file, this helps further encapsulate the
>> concept.
>
>What is userspace supposed to *do* with this, though?

This came as a scratch to my own itch. I wanted to start testing
more tiering patches overall that I see pop up, and wanted a way
to differentiate the slow vs the fast memories in order to better
configure workload(s) working set sizes beyond what is your typical
grep MemTotal /proc/meminfo. If there is a better way I'm all
for it.

>
>What does "attached" mean?

I'll rephrase.

>Isn't it just asking for trouble to add (known) redundancy to the ABI?
>It seems like a recipe for future inconsistency.

Perhaps. It was mostly about the fact that the notion of top tier
could also change as technology evolves.

Thanks,
Davidlohr

  reply	other threads:[~2022-04-18 16:56 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-16  5:38 [PATCH RFC lsfmm 0/6] mm: proactive reclaim and memory tiering topics Davidlohr Bueso
2022-04-16  5:38 ` [PATCH 1/6] drivers/base/node: cleanup register_node() Davidlohr Bueso
2022-04-25 22:30   ` Adam Manzanares
2022-05-03 18:17   ` David Hildenbrand
2022-05-04  4:33   ` David Rientjes
2022-04-16  5:38 ` [PATCH 2/6] mm/vmscan: use node_is_toptier helper in node_reclaim Davidlohr Bueso
2022-04-25 22:32   ` Adam Manzanares
2022-05-04  4:33   ` David Rientjes
2022-05-04  7:26   ` Jagdish Gediya
2022-05-31 11:50   ` Aneesh Kumar K.V
2022-06-01  6:12     ` Ying Huang
2022-06-01 14:00       ` Davidlohr Bueso
2022-04-16  5:38 ` [PATCH 3/6] mm: make __node_reclaim() more flexible Davidlohr Bueso
2022-04-16  5:39 ` [PATCH 4/6] mm: introduce per-node proactive reclaim interface Davidlohr Bueso
2022-04-19  0:00   ` Tim Chen
2022-04-16  5:39 ` [PATCH 5/6] mm/migration: export demotion_path of a node via sysfs Davidlohr Bueso
2022-04-22 17:31   ` Yang Shi
2022-04-22 17:33     ` Yang Shi
2022-04-22 17:50       ` Davidlohr Bueso
2022-04-17  3:49 ` [PATCH 6/6] mm/migrate: export whether or not node is toptier in sysf Davidlohr Bueso
2022-04-18 15:34   ` Dave Hansen
2022-04-18 16:45     ` Davidlohr Bueso [this message]
2022-04-18 16:50       ` Dave Hansen
2022-04-18 17:01         ` Davidlohr Bueso
2022-04-22 17:37   ` Yang Shi

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