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Message-ID: <080d64c3-1289-49c4-f4a0-105e5266a6f0@linux.ibm.com>
Date:   Mon, 13 Jun 2022 18:58:43 +0530
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Subject: Re: [PATCH v6 01/13] mm/demotion: Add support for explicit memory
 tiers
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To:     Johannes Weiner <hannes@cmpxchg.org>,
        Ying Huang <ying.huang@intel.com>
Cc:     linux-mm@kvack.org, akpm@linux-foundation.org,
        Wei Xu <weixugc@google.com>, Greg Thelen <gthelen@google.com>,
        Yang Shi <shy828301@gmail.com>,
        Davidlohr Bueso <dave@stgolabs.net>,
        Tim C Chen <tim.c.chen@intel.com>,
        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>
References: <20220610135229.182859-1-aneesh.kumar@linux.ibm.com>
 <20220610135229.182859-2-aneesh.kumar@linux.ibm.com>
 <7e0b41422dbd0976cb43c2f126e9371d5e311e77.camel@intel.com>
 <48096ad7-ce6d-79b7-1edd-7e6652ab2a4d@linux.ibm.com>
 <a88bd25fc77252dee4f895f3a9b2c1f6ebb5169e.camel@intel.com>
 <Yqc4nSEuso+YmPE7@cmpxchg.org>
From:   Aneesh Kumar K V <aneesh.kumar@linux.ibm.com>
In-Reply-To: <Yqc4nSEuso+YmPE7@cmpxchg.org>
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On 6/13/22 6:46 PM, Johannes Weiner wrote:
> On Mon, Jun 13, 2022 at 01:30:08PM +0800, Ying Huang wrote:
>> On Mon, 2022-06-13 at 09:01 +0530, Aneesh Kumar K V wrote:
>>> On 6/13/22 8:52 AM, Ying Huang wrote:
>>>> On Fri, 2022-06-10 at 19:22 +0530, Aneesh Kumar K.V wrote:
>>>>> +config TIERED_MEMORY
>>>>> +	def_bool NUMA
>>>>> +
>>>>
>>>> As Yang pointed out, why not just use CONFIG_NUMA?  I suspect the
>>>> added value of CONIFIG_TIRED_MEMORY.
>>>
>>> I decided to use TIERED_MEMORY to bring more clarity. It should be same
>>> now that we have moved CONFIG_MIGRATION dependencies to runtime. IMHO
>>> having CONFIG_TIERED_MEMORY is better than using CONFIG_NUMA.
>>
>> I don't think CONFIG_TIERED_MEMORY bring no much value.  It's better
>> to use CONFIG_NUMA directly.  But this is just my opinion.
> 
> I agree. As long as it's always built with CONFIG_NUMA, it's simply
> NUMA code. Easy enough to modularize it later if somebody really wants
> this to be configurable separately.

I was comparing,

#ifdef CONFIG_TIERED_MEMORY
struct memory_tier {

vs

#ifdef CONFIG_NUMA
struct memory_tier {

I will switch to CONFIG_NUMA in the next update since you are not 
finding it beneficial.

-aneesh