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From:   "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
To:     Tim Chen <tim.c.chen@linux.intel.com>, linux-mm@kvack.org,
        akpm@linux-foundation.org
Cc:     Tim Chen <tim.c.chen@linux.intel.com>, Wei Xu <weixugc@google.com>,
        Huang Ying <ying.huang@intel.com>,
        Greg Thelen <gthelen@google.com>,
        Yang Shi <shy828301@gmail.com>,
        Davidlohr Bueso <dave@stgolabs.net>,
        Brice Goglin <brice.goglin@gmail.com>,
        Michal Hocko <mhocko@kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Hesham Almatary <hesham.almatary@huawei.com>,
        Dave Hansen <dave.hansen@intel.com>,
        Jonathan Cameron <Jonathan.Cameron@huawei.com>,
        Alistair Popple <apopple@nvidia.com>,
        Dan Williams <dan.j.williams@intel.com>,
        Feng Tang <feng.tang@intel.com>,
        Jagdish Gediya <jvgediya@linux.ibm.com>,
        Baolin Wang <baolin.wang@linux.alibaba.com>,
        David Rientjes <rientjes@google.com>,
        Shakeel Butt <shakeelb@google.com>
Subject: Re: [RFC PATCH 1/3] mm/memory-tiers Add functions for tier memory
 usage in a cgroup
In-Reply-To: <94a10c772c50d378b81dad654476551bfc50e3d7.1655242024.git.tim.c.chen@linux.intel.com>
References: <cover.1655242024.git.tim.c.chen@linux.intel.com>
 <94a10c772c50d378b81dad654476551bfc50e3d7.1655242024.git.tim.c.chen@linux.intel.com>
Date:   Tue, 21 Jun 2022 09:48:50 +0530
Message-ID: <875ykuabth.fsf@linux.ibm.com>
Content-Type: text/plain
MIME-Version: 1.0
Precedence: bulk

Tim Chen <tim.c.chen@linux.intel.com> writes:

 +unsigned long mem_cgroup_toptier_usage(struct mem_cgroup *memcg)
> +{
> +	struct memory_tier *top_tier;
> +
> +	top_tier = list_first_entry(&memory_tiers, struct memory_tier, list);
> +	if (top_tier)
> +		return mem_cgroup_memtier_usage(memcg, top_tier);
> +	else
> +		return 0;
> +}

As discussed here, we would want to consider all memory tiers that got
compute as top tier.

https://lore.kernel.org/linux-mm/11f94e0c50f17f4a6a2f974cb69a1ae72853e2be.camel@intel.com

V6 patchset actually walk the full memory tier hierarchy reverse and consider any
memory tier with higher or equal rank value than the first memory tier with CPU as top tier.

https://lore.kernel.org/linux-mm/20220610135229.182859-12-aneesh.kumar@linux.ibm.com

-aneesh