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Thu, 16 Jun 2022 04:47:41 +0000 (GMT) Received: from [9.109.205.170] (unknown [9.109.205.170]) by d06av25.portsmouth.uk.ibm.com (Postfix) with ESMTP; Thu, 16 Jun 2022 04:47:41 +0000 (GMT) Message-ID: Date: Thu, 16 Jun 2022 10:17:40 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.10.0 Subject: Re: [PATCH v5 1/9] mm/demotion: Add support for explicit memory tiers Content-Language: en-US To: Wei Xu , Ying Huang Cc: Johannes Weiner , Jonathan Cameron , Linux MM , Andrew Morton , Greg Thelen , Yang Shi , Davidlohr Bueso , Tim C Chen , Brice Goglin , Michal Hocko , Linux Kernel Mailing List , Hesham Almatary , Dave Hansen , Alistair Popple , Dan Williams , Feng Tang , Jagdish Gediya , Baolin Wang , David Rientjes References: <02ee2c97-3bca-8eb6-97d8-1f8743619453@linux.ibm.com> <20220609152243.00000332@Huawei.com> <20220610105708.0000679b@Huawei.com> <4297bd21-e984-9d78-2bca-e70c11749a72@linux.ibm.com> <42f536af-b17d-b001-7b6b-2c6b928f3ecf@linux.ibm.com> <2b261518bbb5b8466301f8ab978f408141fa6e68.camel@intel.com> From: Aneesh Kumar K V In-Reply-To: Content-Type: text/plain; charset=UTF-8 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: y0ubvEXHPYVM4LKj3n6euztfCvr1A9fm X-Proofpoint-ORIG-GUID: pgtDHW9V_y_QlXsQnyTg-e-HOnbz5teF 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:18.0.874,Hydra:6.0.517,FMLib:17.11.64.514 definitions=2022-06-16_01,2022-06-15_01,2022-02-23_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxlogscore=993 priorityscore=1501 suspectscore=0 impostorscore=0 adultscore=0 phishscore=0 bulkscore=0 mlxscore=0 malwarescore=0 clxscore=1015 lowpriorityscore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2204290000 definitions=main-2206160016 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 6/16/22 9:15 AM, Wei Xu wrote: > On Wed, Jun 15, 2022 at 6:11 PM Ying Huang wrote: >> >> On Tue, 2022-06-14 at 14:56 -0400, Johannes Weiner wrote: >>> On Tue, Jun 14, 2022 at 01:31:37PM +0530, Aneesh Kumar K V wrote: .... >> As Jonathan Cameron pointed, we may need the memory tier ID to be >> stable if possible. I know this isn't a easy task. At least we can >> make the default memory tier (CPU local DRAM) ID stable (for example >> make it always 128)? That provides an anchor for users to understand. > > One of the motivations of introducing "rank" is to allow memory tier > ID to be stable, at least for the well-defined tiers such as the > default memory tier. The default memory tier can be moved around in > the tier hierarchy by adjusting its rank position relative to other > tiers, but its device ID can remain the same, e.g. always 1. > With /sys/devices/system/memtier/default_tier userspace will be able query the default tier details. Did you get to look at https://lore.kernel.org/linux-mm/7b72ccf4-f4ae-cb4e-f411-74d055482026@linux.ibm.com Any reason why that will not work with all the requirements we had? -aneesh