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Message-ID: <Yqm+ZnHfkxuyuzyD@dhcp22.suse.cz>
Date: Wed, 15 Jun 2022 13:11:34 +0200
From: Michal Hocko <mhocko@...e.com>
To: Tim Chen <tim.c.chen@...ux.intel.com>
Cc: linux-mm@...ck.org, akpm@...ux-foundation.org,
Wei Xu <weixugc@...gle.com>, Huang Ying <ying.huang@...el.com>,
Greg Thelen <gthelen@...gle.com>,
Yang Shi <shy828301@...il.com>,
Davidlohr Bueso <dave@...olabs.net>,
Brice Goglin <brice.goglin@...il.com>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Hesham Almatary <hesham.almatary@...wei.com>,
Dave Hansen <dave.hansen@...el.com>,
Jonathan Cameron <Jonathan.Cameron@...wei.com>,
Alistair Popple <apopple@...dia.com>,
Dan Williams <dan.j.williams@...el.com>,
Feng Tang <feng.tang@...el.com>,
Jagdish Gediya <jvgediya@...ux.ibm.com>,
Baolin Wang <baolin.wang@...ux.alibaba.com>,
David Rientjes <rientjes@...gle.com>,
"Aneesh Kumar K . V" <aneesh.kumar@...ux.ibm.com>,
Shakeel Butt <shakeelb@...gle.com>
Subject: Re: [RFC PATCH 0/3] Cgroup accounting of memory tier usage
On Tue 14-06-22 15:25:32, Tim Chen wrote:
> For controlling usage of a top tiered memory by a cgroup, accounting
> of top tier memory usage is needed. This patch set implements the
> following:
>
> Patch 1 introduces interface and simple implementation to retrieve
> cgroup tiered memory usage
> Patch 2 introduces more efficient accounting with top tier memory page counter
> Patch 3 provides a sysfs interface to repot the the top tiered memory
> usage.
I guess you meant cgroupfs here, right?
> The patchset works with Aneesh's v6 memory-tiering implementation [1].
> It is a preparatory patch set before introducing features to
> control top tiered memory in cgroups.
>
> I'll like to first get feedback to see if
> (1) Controllng the topmost tiered memory is enough
> or
> (2) Multiple tiers at the top levels need to be grouped into "toptier"
> or
> (3) There are use cases not covered by (1) and (2).
I would start by asking why do we need a dedicated interface in the
first place. Why the existing numa_stat is not a proper interface. Right
now we only report LRU per node stats. Is this insufficient?
What is userspace expect to do based on the reported data?
--
Michal Hocko
SUSE Labs
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