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Fri, 2 Sep 2022 06:31:44 +0000 (GMT) Received: from [9.43.64.219] (unknown [9.43.64.219]) by d06av22.portsmouth.uk.ibm.com (Postfix) with ESMTP; Fri, 2 Sep 2022 06:31:43 +0000 (GMT) Message-ID: <2b4ddc45-74ae-27df-d973-6724f61f4e18@linux.ibm.com> Date: Fri, 2 Sep 2022 12:01:43 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.2.0 Subject: Re: [PATCH v3 updated] mm/demotion: Expose memory tier details via sysfs Content-Language: en-US To: "Huang, Ying" Cc: Wei Xu , Johannes Weiner , Linux MM , Andrew Morton , Yang Shi , Davidlohr Bueso , Tim C Chen , Michal Hocko , Linux Kernel Mailing List , Hesham Almatary , Dave Hansen , Jonathan Cameron , Alistair Popple , Dan Williams , jvgediya.oss@gmail.com, Bharata B Rao , Greg Thelen References: <20220830081736.119281-1-aneesh.kumar@linux.ibm.com> <87tu5rzigc.fsf@yhuang6-desk2.ccr.corp.intel.com> <87pmgezkhp.fsf@yhuang6-desk2.ccr.corp.intel.com> <87fshaz63h.fsf@yhuang6-desk2.ccr.corp.intel.com> <698120ce-d4df-3d13-dea9-a8f5c298783c@linux.ibm.com> <87bkryz4nh.fsf@yhuang6-desk2.ccr.corp.intel.com> From: Aneesh Kumar K V In-Reply-To: <87bkryz4nh.fsf@yhuang6-desk2.ccr.corp.intel.com> Content-Type: text/plain; charset=UTF-8 X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: XGAvjo26pnFRCg8RdgzpRmXKbfarDkBy X-Proofpoint-GUID: 3ihvSZw8bWIPRqEMAATZcDXLUDuPTf5X Content-Transfer-Encoding: 7bit X-Proofpoint-UnRewURL: 0 URL was un-rewritten MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.895,Hydra:6.0.517,FMLib:17.11.122.1 definitions=2022-09-01_12,2022-08-31_03,2022-06-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxscore=0 lowpriorityscore=0 phishscore=0 priorityscore=1501 mlxlogscore=999 impostorscore=0 bulkscore=0 malwarescore=0 clxscore=1015 adultscore=0 spamscore=0 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2207270000 definitions=main-2209020026 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/2/22 11:42 AM, Huang, Ying wrote: > Aneesh Kumar K V writes: > >> On 9/2/22 11:10 AM, Huang, Ying wrote: >>> Aneesh Kumar K V writes: >>> >>>> On 9/2/22 10:39 AM, Wei Xu wrote: >>>>> On Thu, Sep 1, 2022 at 5:33 PM Huang, Ying wrote: >>>>>> >>>>>> Aneesh Kumar K V writes: >>>>>> >>>>>>> On 9/1/22 12:31 PM, Huang, Ying wrote: >>>>>>>> "Aneesh Kumar K.V" writes: >>>>>>>> >>>>>>>>> This patch adds /sys/devices/virtual/memory_tiering/ where all memory tier >>>>>>>>> related details can be found. All allocated memory tiers will be listed >>>>>>>>> there as /sys/devices/virtual/memory_tiering/memory_tierN/ >>>>>>>>> >>>>>>>>> The nodes which are part of a specific memory tier can be listed via >>>>>>>>> /sys/devices/virtual/memory_tiering/memory_tierN/nodes >>>>>>>> >>>>>>>> I think "memory_tier" is a better subsystem/bus name than >>>>>>>> memory_tiering. Because we have a set of memory_tierN devices inside. >>>>>>>> "memory_tier" sounds more natural. I know this is subjective, just my >>>>>>>> preference. >>>>>>>> >>>> >>>> >>>> I missed replying to this earlier. I will keep memory_tiering as subsystem name in v4 >>>> because we would want it to a susbsystem where all memory tiering related details can be found >>>> including memory type in the future. This is as per discussion >>>> >>>> https://lore.kernel.org/linux-mm/CAAPL-u9TKbHGztAF=r-io3gkX7gorUunS2UfstudCWuihrA=0g@mail.gmail.com >>> >>> I don't think that it's a good idea to mix 2 types of devices in one >>> subsystem (bus). If my understanding were correct, that breaks the >>> driver core convention. >>> >> >> All these are virtual devices .I am not sure i follow what you mean by 2 types of devices. >> memory_tiering is a subsystem that represents all the details w.r.t memory tiering. It shows >> details of memory tiers and can possibly contain details of different memory types . > > IMHO, memory_tier and memory_type are 2 kind of devices. They have > almost totally different attributes (sysfs file). So, we should create > 2 buses for them. Each has its own attribute group. "virtual" itself > isn't a subsystem. Considering both the details are related to memory tiering, wouldn't it be much simpler we consolidate them within the same subdirectory? I am still not clear why you are suggesting they need to be in different sysfs hierarchy. It doesn't break any driver core convention as you mentioned earlier. /sys/devices/virtual/memory_tiering/memory_tierN /sys/devices/virtual/memory_tiering/memory_typeN -aneesh