Messages in this thread | | | From | "Huang, Ying" <> | Subject | Re: [RFC PATCH 2/2] mm/demotion: Expose memory tier details via sysfs | Date | Fri, 26 Aug 2022 12:31:10 +0800 |
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"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> writes:
> All allocated memory tiers will be listed as > /sys/devices/virtual/memtier/memtierN/ > > Each memtier directory contains symbolic link for the memory types > that are part of the memory tier. A directory hierarchy looks like > > :/sys/devices/virtual/memtier# tree memtier512/ > memtier512/
So you suggest to use abstract_distance_start as memory tier ID? That will make memory tier ID stable unless we change abstract distance chunk size or abstract distance division points. That is, we have at least 2 choices here
1. memory_tier0, memory_tier1, memory_tier2, ...
The ID will start from 0. This is easy to understand by users. The main drawback is that the memory tier ID may be changed when a NUMA node is onlined/offlined. That is, the memory tier ID is relatively unstable.
2. memory_tier<abstract_distance_start1>, memory_tier<abstract_distance_start2>, ...
The ID will be discontinuous. So it's not as intuitive as 0,1,2,.... The main advantage is that the memory tier ID will not change when a NUMA node is onlined/offlined. The ID will be changed only when we change abstract distance chunk size or abstract distance division points. That is considered relatively seldom.
Personally, I prefer the 2nd choice too. But I want to collect opinions from other people too.
> ├── memtype1 -> ../memtype1 > ├── memtype2 -> ../memtype2
I think abstract_distance_start and abstract_distance_end is the key information of a memory tier too. So we should show them here.
> ├── subsystem -> ../../../../bus/memtier > └── uevent > > The nodes which are part of a specific memory type can be listed via > /sys/devices/system/memtier/memtypeN/nodes. > > The adistance value of a specific memory type can be listed via > /sys/devices/system/memtier/memtypeN/adistance. > > Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Best Regards, Huang, Ying
[snip]
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