Reading  /proc/pressure/* with

 ll  /proc/pressure/*
 -r--r--r-- 1 root root 0 Mar  5 10:09 /proc/pressure/cpu
 -r--r--r-- 1 root root 0 Mar  5 10:09 /proc/pressure/io
 -r--r--r-- 1 root root 0 Mar  5 10:09 /proc/pressure/memory

leads to

strace -s 256 -e openat,read head /proc/pressure/*
openat(AT_FDCWD, "/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
openat(AT_FDCWD, "/lib64/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
read(3,
"\177ELF\2\1\1\3\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\220<\2\0\0\0\0\0@\0\0\0\0\0\0\08\353\37\0\0\0\0\0\0\0\0\0@\08\0\f\0@\0H\0G\0\6\0\0\0\4\0\0\0@\0\0\0\0\0\0\0@\0\0\0\0\0\0\0@\0\0\0\0\0\0\0\240\2\0\0\0\0\0\0\240\2\0\0\0\0\0\0\10\0\0\0\0\0\0\0\3\0\0\0\4\0\0\0P\364\30\0\0\0\0\0P\364\30\0\0\0\0\0P\364\30\0\0\0\0\0\34\0\0\0\0\0\0\0\34\0\0\0\0\0\0\0\20\0\0\0\0\0\0\0\1\0\0\0\4\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\350\24\2\0\0\0\0\0\350\24\2\0\0\0\0\0\0\20\0\0\0\0\0\0\1\0\0\0\5\0\0\0\0
\2\0\0\0\0\0\0 \2\0\0\0\0\0"..., 832) = 832
openat(AT_FDCWD, "/proc/pressure/cpu", O_RDONLY) = 3
==> /proc/pressure/cpu <==
read(3, 0x7ffc457b25c0, 8192)           = -1 EOPNOTSUPP (Operation not
supported)
head: error reading '/proc/pressure/cpu': Operation not supported
openat(AT_FDCWD, "/proc/pressure/io", O_RDONLY) = 3

==> /proc/pressure/io <==
read(3, 0x7ffc457b25c0, 8192)           = -1 EOPNOTSUPP (Operation not
supported)
head: error reading '/proc/pressure/io': Operation not supported
openat(AT_FDCWD, "/proc/pressure/memory", O_RDONLY) = 3

==> /proc/pressure/memory <==
read(3, 0x7ffc457b25c0, 8192)           = -1 EOPNOTSUPP (Operation not
supported)
head: error reading '/proc/pressure/memory': Operation not supported
+++ exited with 1 +++