Get accuracy memory and cpu limits inside container

[0xyjk]

Context

• current implementation for get memory limits: https://github.com/0xPolygonHermez/zkevm-prover/blob/94f56629e1962eec7b1ae9a055213d97f57863bf/src/utils/utils.cpp#L61
• current implementation for get cpu limits: https://github.com/0xPolygonHermez/zkevm-prover/blob/94f56629e1962eec7b1ae9a055213d97f57863bf/src/utils/utils.cpp#L425

Problems

if program running in a docker container with cgroup limits, the way to get CPU/Memory limits is not accuracy which potentially will cause OOM

Solution

Get Memory Limit

try get memory limit from /sys/fs/cgroup/memory/memory.limit_in_bytes, if the value is 0 or large than /proc/meminfo, fallback to use the mem info inside /proc/meminfo

Get CPU Limit

try to caculate CPU Core number from /sys/fs/cgroup/cpu/cpu.cfs_quota_us Div /sys/fs/cgroup/cpu/cpu.cfs_period_us, if it's not a valid number, then fallback to omp_get_num_procs()

Refs

• https://gist.github.com/janvorli/0614a42e612965ea3ad56d00743dc7a2
• https://stackoverflow.com/questions/65551215/get-docker-cpu-memory-limit-inside-container
• https://facebookmicrosites.github.io/cgroup2/docs/cpu-controller.html
• https://facebookmicrosites.github.io/cgroup2/docs/memory-controller.html