1*20b51af1SHuang YingWhat: /sys/kernel/mm/numa/ 2*20b51af1SHuang YingDate: June 2021 3*20b51af1SHuang YingContact: Linux memory management mailing list <linux-mm@kvack.org> 4*20b51af1SHuang YingDescription: Interface for NUMA 5*20b51af1SHuang Ying 6*20b51af1SHuang YingWhat: /sys/kernel/mm/numa/demotion_enabled 7*20b51af1SHuang YingDate: June 2021 8*20b51af1SHuang YingContact: Linux memory management mailing list <linux-mm@kvack.org> 9*20b51af1SHuang YingDescription: Enable/disable demoting pages during reclaim 10*20b51af1SHuang Ying 11*20b51af1SHuang Ying Page migration during reclaim is intended for systems 12*20b51af1SHuang Ying with tiered memory configurations. These systems have 13*20b51af1SHuang Ying multiple types of memory with varied performance 14*20b51af1SHuang Ying characteristics instead of plain NUMA systems where 15*20b51af1SHuang Ying the same kind of memory is found at varied distances. 16*20b51af1SHuang Ying Allowing page migration during reclaim enables these 17*20b51af1SHuang Ying systems to migrate pages from fast tiers to slow tiers 18*20b51af1SHuang Ying when the fast tier is under pressure. This migration 19*20b51af1SHuang Ying is performed before swap. It may move data to a NUMA 20*20b51af1SHuang Ying node that does not fall into the cpuset of the 21*20b51af1SHuang Ying allocating process which might be construed to violate 22*20b51af1SHuang Ying the guarantees of cpusets. This should not be enabled 23*20b51af1SHuang Ying on systems which need strict cpuset location 24*20b51af1SHuang Ying guarantees. 25