Local execution on Apple Silicon Macbook M1: reservation cannot be satisfied

[CharlelieLrt]

I have been running simple cunumeric scripts on a Macbook M1 (macOS 12.6.7) with legate --cpus 1 my_script.py.
Cunumeric was built with the config described in another issue (nv-legate/legate.core#904).
Everything seems to be running just fine, except that I am always getting a warning:

[0 - 100f84580]    0.000023 {4}{threads}: reservation ('Python-1 proc 1d00000000000003') cannot be satisfied

The output of -ll:show_rsrv shows:

core map {
  domain 0 {
    core 0 { }
  }
}
dedicated worker (generic) #1: allocated <>
dedicated worker (generic) #2: allocated <>
utility proc 1d00000000000000: allocated <>
utility proc 1d00000000000001: allocated <>
CPU proc 1d00000000000002: allocated <>
Python-1 proc 1d00000000000003: allocated <>

This suggests that there are not enough cores on my machine for the reservation, correct? But sysctl -n hw.ncpu shows that I have 10 cores available on my machine.
I am wondering what I am missing there.

[manopapad]

There are enough cores, but Realm cannot pin threads to cores on MacOS, because MacOS doesn't provide the relevant API. This message is Realm warning that it can't guarantee that application threads will have uninterrupted use of a dedicated core. It's confusing that the same message could mean "you're oversubscribing your cores" in other contexts.

In any case, we've asked the Realm team to allow us to explicitly disable thread pinning (thus skipping this warning) on platforms where we know it can't work.

[CharlelieLrt]

Ok got it, thanks for the clarification.