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X-OriginatorOrg: micron.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 05 Dec 2023 09:20:07.8465 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 48b3770a-24d5-49f9-38d9-08dbf5735fbe X-MS-Exchange-CrossTenant-Id: f38a5ecd-2813-4862-b11b-ac1d563c806f X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=f38a5ecd-2813-4862-b11b-ac1d563c806f;Ip=[137.201.242.130];Helo=[mail.micron.com] X-MS-Exchange-CrossTenant-AuthSource: DS2PEPF00003441.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH0PR08MB8732 X-Rspam-User: X-Stat-Signature: g3muy9racphe3nwftw7uc5if38s8r5pa X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: CAFC5140006 X-HE-Tag: 1701768012-691327 X-HE-Meta: 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 yaZUCB95 opiReB9KwXR/s0wSXkvfzPor2Y7s/mh8Kcqsw7wW5IrkV/r8K1EwIXBnIb1AcKyv70NMGT9yDzvBYafrH5VBJS+8msc4oXoluloquHaRr3b7zzpKxP5+MIMRdj6kdOTAvMQOcbCQo6BXEe0nw+07u8TbQLXb2P1LVz2grT1gLaA0ikOAUoXsH/DECXlPldxiEo5VS9qE1w575prutR7ABxDKxW2iXTlSndknZgDzwBlYJlIFoNl4WCT6wfcDtZ5WAGAVmDITR5eiElnSmvqEz2tXSQ3BmnnS7Sgql2U1h/n5d7SkA5ViIqXVvRqn34O0auBnu39yu+VwUjF0dagor8c+qv5aeQKmU94aJ2onPKprU7tYJdXU/wIWIM5Zipv1qLc3f X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: >On Tue 05-12-23 14:12:17, Srinivasulu Thanneeru wrote:=0D >> =0D >> =0D >> On 12/5/2023 2:05 PM, Michal Hocko wrote:=0D >> > CAUTION: EXTERNAL EMAIL. Do not click links or open attachments unless= you recognize the sender and were expecting this message.=0D >> > =0D >> > =0D >> > On Tue 05-12-23 01:26:07, Srinivasulu Thanneeru wrote:=0D >> > > =0D >> > > =0D >> > > On 12/4/2023 9:13 PM, Michal Hocko wrote:=0D >> > > > CAUTION: EXTERNAL EMAIL. Do not click links or open attachments un= less you recognize the sender and were expecting this message.=0D >> > > > =0D >> > > > =0D >> > > > On Fri 01-12-23 03:34:20, sthanneeru.opensrc@micron.com wrote:=0D >> > > > > From: Srinivasulu Thanneeru =0D >> > > > > =0D >> > > > > The memory tiers feature allows nodes with similar memory types= =0D >> > > > > or performance characteristics to be grouped together in a=0D >> > > > > memory tier. However, there is currently no provision for=0D >> > > > > moving a node from one tier to another on demand.=0D >> > > > =0D >> > > > Could you expand on why this is really needed/necessary? What is t= he=0D >> > > > actual usecase?=0D >> > > =0D >> > > Hi Michal Hock,=0D >> > > =0D >> > > Following two use-cases we have observed.=0D >> > > 1. It is not accurate to group similar memory types in the same tier= ,=0D >> > > because even similar memory types may have different speed grade= s.=0D >> > =0D >> > Presumably they are grouped based on a HW configuration. Does that mea= n=0D >> > that the configuration is wrong? Are you trying to workaround that by= =0D >> > this interface?=0D >> > =0D >> > > 2. Some systems boots up with CXL devices and DRAM on the same memor= y-tier,=0D >> > > we need a way to move the CXL nodes to the correct tier from the use= r space.=0D >> > =0D >> > Again, could you expand a bit more and explain why this cannot be=0D >> > configured automatically?=0D >> =0D >> Yes, in both cases above, if hardware not automatically populated proper= ly,=0D >> in that case this interface would help to correct it from user space.=0D >> =0D >> We had observed case-2 in our setups.=0D >=0D >How hard it is to address this at the HW level?=0D >=0D >Btw. this is really important piece of context that should be part of=0D >the changelog. Quite honestly introducing user interfaces solely to=0D >workaround HW issues seems a rather weak justification. Are there any=0D >usecases you can think of where this would be useful?=0D >=0D >-- =0D >Michal Hocko=0D >SUSE Labs=0D =0D Hello Michal Hocko,=0D =0D It will be useful if we want interleave weights to be applied on memory= tiers=0D instead of nodes.=0D Also, for near memory processing use cases where some accelerator would= like=0D to have hot pages migrated to a different node with HBM, pmem or CXL instea= d of=0D CPU attached memory for performing it's operations quicker.=0D =0D There was a prior discussion on this functionality in a previous thread, wh= ere=0D Huang Ying thought this might be a useful feature to overcome limitations o= f=0D systems where nodes with different bandwidth characteristics are grouped in= =0D a single tier.=0D =0D https://lore.kernel.org/lkml/87a5rw1wu8.fsf@yhuang6-desk2.ccr.corp.intel.co= m/=0D =0D --=0D Best Regards,=0D Ravi Jonnalagadda=