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The >>> >>> I continue to think we should not do this. >>> >> >> I am unclear about the benefits of the patchset, I have not tested >> it or reviewed the latest revision. My big concern was that top-tier >> might not always be suitable. > > So you are saying that we should have a capability to promote accessed pages > from lower tier to an other tier that is not classified as top tier? Is that > non-top tier node the one which generates accesses? > Yes, a top tier node could be CPU less for example. >> >> I see that there are some numbers posted, but I find this weird >> "After the graph creation, the processes are stopped and data is migrated >> to CXL node 2 before continuing so that BFS phase starts accessing lower >> tier memory." Why not allocate everything on CXL node 2? > > In the ideal scenario, the benefit is to see if any pages that land up on lower > tier get identified as hot and get promoted. That means we need to create an > over-committed scenario where the pages get demoted first. I have provided Why do the pages need to get demoted? Why not allocate them from the lower tier to show that promotion upwards is helpful > numbers from such cases in my previous versions. The problem with this case is > that the base hot page promotion (NUMAB2) hasn't shown any benefit at all with > my micro-benchmark - Ref: > https://lore.kernel.org/linux-mm/868004d8-bb8e-4800-9fdd-ade48e95fe3b@amd.com/ > > Same has been observed with redis-memtier benchmark - > https://lore.kernel.org/linux-mm/957f2242-56d4-4bf0-8aeb-9d60fbea8c8c@amd.com/ > > Instead what I am doing here is to take out demotion from the scenario but still > retain the access pattern of the benchmark by pushing out the data to lower tier > when the benchmark reaches steady allocation state. > Balbir