On 8/26/22 7:20 AM, Huang, Ying wrote: > "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxx> writes: > >> This patch adds /sys/devices/virtual/memtier/ where all memory tier related >> details can be found. All allocated memory types will be listed there as >> /sys/devices/virtual/memtier/memtypeN/ > > Another choice is to make memory types and memory tiers system devices. > That is, > > /sys/devices/system/memory_type/memory_typeN > /sys/devices/system/memory_tier/memory_tierN > subsys_system_register() documentation says * Do not use this interface for anything new, it exists for compatibility * with bad ideas only. New subsystems should use plain subsystems; and * add the subsystem-wide attributes should be added to the subsystem * directory itself and not some create fake root-device placed in * /sys/devices/system/<name>. memtier being a virtual device, I was under the impression that /sys/devices/virtual is the recommended place. > That looks more natural to me. Because we already have "node" and > "memory" devices there. Why don't you put memory types and memory tiers > there? > > And, I think we shouldn't put "memory_type" in the "memory_tier" > directory. "memory_type" isn't a part of "memory_tier". > I was looking consolidating both memory tier and memory type into the same sysfs subsystem. Your recommendation imply we create two subsystem memory_tier and memtype. I was trying to avoid that. May be a generic term like "memory_tiering" can help to consolidate all tiering related details there? >> The nodes which are part of a specific memory type can be listed via >> /sys/devices/system/memtier/memtypeN/nodes. > > How about create links to /sys/devices/system/node/nodeN in > "memory_type". But I'm OK to have "nodes" file too. > >> The adistance value of a specific memory type can be listed via >> /sys/devices/system/memtier/memtypeN/adistance. >> >> A directory listing looks like: >> :/sys/devices/virtual/memtier# tree memtype1 >> memtype1 >> ├── adistance > > Why not just use "abstract_distance"? This is user space interface, > it's better to be intuitive. > >> ├── nodes >> ├── subsystem -> ../../../../bus/memtier >> └── uevent >> >> Since we will be using struct device to expose details via sysfs, drop struct >> kref and use struct device for refcounting the memtype. >> > > Best Regards, > Huang, Ying
