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