From: Dave Hansen <dave.hansen@intel.com>
To: 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 09:50:33 -0700 [thread overview]
Message-ID: <9961bda1-687a-a681-743e-7eb7b9f6f751@intel.com> (raw)
In-Reply-To: <20220418164503.jfips3aiwhnlfjrq@offworld>
On 4/18/22 09:45, Davidlohr Bueso wrote:
> 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.
But how does this help you? Does it save you a few lines in a shell
script to find the nodes that have memory and CPUs?
>> 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.
It seems like something arbitrary that everyone will just disagree on.
I think we should try to stick to cold, hard facts as must as possible
rather than trying to have the *kernel* dictate as a policy what is fast
versus slow.
next prev parent reply other threads:[~2022-04-18 16:50 UTC|newest]
Thread overview: 23+ 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
2022-04-16 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
2022-04-18 16:50 ` Dave Hansen [this message]
2022-04-22 17:37 ` Yang Shi
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