Bug 2080227

Description of problem:
Customer reported that tuned doesn't seem to be able to handle too many profile switches.

Version-Release number of selected component (if applicable):
tuned-2.16.0-1.el8

How reproducible:
Always

Steps to Reproduce:
1. Run this loop:
while true; do tuned-adm profile virtual-guest; done
2. Wait a few minutes to reproduce the issue. You can monitor the nofile for the tuned pid with lsof to see when it will fail.

Actual results:
# tuned-adm profile virtual-guest
Requested profile 'virtual-guest' doesn't exist.

Additional info:
- the profile cannot be read because the nofile limit is reached.
- restarting the daemon fixes the issue.
- disabling the CPU plugin workarounds the issue.
- some output from my reproducer:

tuned.log after doing a loop
~~~
2022-04-28 09:50:53,005 INFO     tuned.plugins.plugin_cpu: We are running on an x86 GenuineIntel platform
2022-04-28 09:50:53,005 ERROR    tuned.utils.commands: Executing x86_energy_perf_policy error: [Errno 24] Too many open files
2022-04-28 09:50:53,005 WARNING  tuned.plugins.plugin_cpu: unable to run x86_energy_perf_policy tool, ignoring CPU energy performance bias, is the tool installed?
2022-04-28 09:50:53,008 INFO     tuned.plugins.base: instance disk: assigning devices vdb, vda, dm-1, dm-0, loop0
2022-04-28 09:54:19,298 ERROR    tuned.daemon.controller: Failed to apply profile 'virtual-guest'
2022-04-28 09:54:22,154 ERROR    tuned.daemon.controller: Failed to apply profile 'virtual-guest'
2022-04-28 09:54:40,129 ERROR    tuned.daemon.controller: Failed to apply profile 'virtual-guest'
2022-04-28 09:57:12,285 ERROR    tuned.daemon.controller: Failed to apply profile 'virtual-guest'
~~~

tuned (PID 983) remains active but does not work anymore (needs a restart).

# ulimit -n
1024

# ls -1 /proc/983/fd/* | wc -l
1024

# ls -l /proc/983/fd/99*
lrwx------. 1 root root 64 Apr 28 09:51 /proc/983/fd/99 -> 'anon_inode:[perf_event]'
lrwx------. 1 root root 64 Apr 28 09:51 /proc/983/fd/990 -> 'anon_inode:[perf_event]'
lrwx------. 1 root root 64 Apr 28 09:51 /proc/983/fd/991 -> 'anon_inode:[perf_event]'
lrwx------. 1 root root 64 Apr 28 09:51 /proc/983/fd/992 -> 'anon_inode:[perf_event]'
lrwx------. 1 root root 64 Apr 28 09:51 /proc/983/fd/993 -> 'anon_inode:[perf_event]'
lrwx------. 1 root root 64 Apr 28 09:51 /proc/983/fd/994 -> 'anon_inode:[perf_event]'
lrwx------. 1 root root 64 Apr 28 09:51 /proc/983/fd/995 -> 'anon_inode:[perf_event]'
lrwx------. 1 root root 64 Apr 28 09:51 /proc/983/fd/996 -> 'anon_inode:[perf_event]'
lrwx------. 1 root root 64 Apr 28 09:51 /proc/983/fd/997 -> 'anon_inode:[perf_event]'
lrwx------. 1 root root 64 Apr 28 09:51 /proc/983/fd/998 -> 'anon_inode:[perf_event]'
lrwx------. 1 root root 64 Apr 28 09:51 /proc/983/fd/999 -> 'anon_inode:[perf_event]'

# lsof -a -p 983 | grep -c a_inode
1013

tuned   983 root 1009u  a_inode               0,14        0    10334 [perf_event]
tuned   983 root 1010u  a_inode               0,14        0    10334 [perf_event]
tuned   983 root 1011u  a_inode               0,14        0    10334 [perf_event]
tuned   983 root 1012u  a_inode               0,14        0    10334 [perf_event]
tuned   983 root 1013u  a_inode               0,14        0    10334 [perf_event]
tuned   983 root 1014u  a_inode               0,14        0    10334 [perf_event]
tuned   983 root 1015u  a_inode               0,14        0    10334 [perf_event]
tuned   983 root 1016u  a_inode               0,14        0    10334 [perf_event]
tuned   983 root 1017u  a_inode               0,14        0    10334 [perf_event]
tuned   983 root 1018u  a_inode               0,14        0    10334 [perf_event]
tuned   983 root 1019u  a_inode               0,14        0    10334 [perf_event]
tuned   983 root 1020u  a_inode               0,14        0    10334 [perf_event]