<sthanneeru.opensrc@xxxxxxxxxx> writes: > From: Srinivasulu Thanneeru <sthanneeru.opensrc@xxxxxxxxxx> > > The memory tiers feature allows nodes with similar memory types > or performance characteristics to be grouped together in a > memory tier. However, there is currently no provision for > moving a node from one tier to another on demand. > > This patch series aims to support node migration between tiers > on demand by sysadmin/root user using the provided sysfs for > node migration. Each tier has a start abstract distance(adistance) > and range. We have discussed migrating nodes (in fact nodes of a memory type) between tiers by sysadmin/root before. The basic idea comes from Johannes. It is summarized in page 11 of [1], [1] https://lpc.events/event/16/contributions/1209/attachments/1042/1995/Live%20In%20a%20World%20With%20Multiple%20Memory%20Types.pdf The abstract distance of a memory type (e.g., GPU HBM) can be adjusted via a sysfs knob (<memory_type>/abstract_distance_offset). I still think that the memory type is better to be used to change the abstract distance of nodes. Do you agree? -- Best Regards, Huang, Ying > To migrate a node to a tier, the corresponding node’s sysfs > adistance_offset is written with a value corresponding to > the tier’s adistance. > > Example: Move node2 to memory tier5 from its default tier(i.e 4) > > 1. Check default values: > $cat /sys/devices/virtual/memory_tiering/memory_tier4/nodelist > 0-2 > > $cat /sys/devices/system/node/node0/adistance_offset > 0 > $cat /sys/devices/system/node/node1/adistance_offset > 0 > $cat /sys/devices/system/node/node2/adistance_offset > 0 > > 2. Move node2 to tier5: > > To move node2 from emory_tier4 (adistance=512) to > emory_tier5 (abstract=640), set the `adistance_offset` of > node 2 to 128 (i.e., 512 + 128 = 640). > > Tier4 adistance start can be derved from tier-id > (i.e for tier4, 4 << 7 = 512). > > $echo 128 > /sys/devices/system/node/node2/adistance_offset > $cat /sys/devices/system/node/node2/adistance_offset > 128 > > 3. Verify node2's tier id: > > $cat /sys/devices/virtual/memory_tiering/memory_tier5/nodelist > 2 > $cat /sys/devices/virtual/memory_tiering/memory_tier4/nodelist > 0-1 > > Srinivasulu Thanneeru (2): > base/node: Add sysfs for adistance_offset > memory tier: Support node migration between tiers > > drivers/base/node.c | 51 +++++++++++++++++++++++ > include/linux/memory-tiers.h | 11 +++++ > include/linux/node.h | 6 +++ > mm/memory-tiers.c | 79 ++++++++++++++++++++---------------- > 4 files changed, 113 insertions(+), 34 deletions(-)
