On Mon, 2022-05-30 at 13:50 +0100, Jonathan Cameron wrote: > > > When discussed offline, Tim Chen pointed out that with the proposed > > interface, it's unconvenient to know the position of a given memory tier > > in all memory tiers. We must sort "rank" of all memory tiers to know > > that. "possible" file can be used for that. Although "possible" file > > can be generated with a shell script, it's more convenient to show it > > directly. > > > > Another way to address the issue is to add memtierN/pos for each memory > > tier as suggested by Tim. It's readonly and will show position of > > "memtierN" in all memory tiers. It's even better to show the relative > > postion to the default memory tier (DRAM with CPU). That is, the > > position of DRAM memory tier is 0. > > > > Unlike memory tier device ID or rank, the position is relative and > > dynamic. > > Hi, > > I'm unconvinced. This is better done with a shell script than > by adding ABI we'll have to live with for ever.. > > I'm no good at shell scripting but this does the job > grep "" tier*/rank | sort -n -k 2 -t : > > tier2/rank:50 > tier0/rank:100 > tier1/rank:200 > tier3/rank:240 > > I'm sure someone more knowledgeable will do it in a simpler fashion still. > > You can argue that $ cat /sys/devices/system/cpu/cpu1/topology/core_siblings f $ cat /sys/devices/system/cpu/cpu1/topology/core_siblings_list 0-3 provide exactly the same information and we should get rid of core_siblings_list. I think core_siblings_list exists to make it easier for a human, so he/she doesn't have to parse the mask, or write a script to find out the ids of CPUs who are siblings. I think in the same spirit, having an interface to allow a human to quickly see the hierachical relationship of tiers relative to each other is helpful. Tim
