Request to add PSI(Pressure stall information) metrics in sosreport.

[amtdas]

Capture PSI(Pressure stall information) metrics in sosreport.

Kernel 4.20 and up includes PSI metrics for CPU, memory and IO. It can be gathered after enabling psi=1 as kernel boot parameter. For RHEL8 it is back-ported to kernel 4.18 release.

$grep -i psi /boot/config-4.18.0-305.17.1.el8_4.x86_64 
CONFIG_PSI=y
CONFIG_PSI_DEFAULT_DISABLED=y

$rpm -qa sos
sos-4.0-11.el8.noarch

$uname -a
Linux rh84 4.18.0-305.17.1.el8_4.x86_64 #1 SMP Mon Aug 30 07:26:31 EDT 2021 x86_64 x86_64 x86_64 GNU/Linux

$grep psi /boot/grub2/grubenv 
kernelopts=root=/dev/mapper/rhel-root ro crashkernel=auto resume=/dev/mapper/rhel-swap rd.lvm.lv=rhel/root rd.lvm.lv=rhel/swap rhgb quiet psi=1

$ls -lrt /proc/pressure/
total 0
-r--r--r--. 1 root root 0 Sep  8 15:05 memory
-r--r--r--. 1 root root 0 Sep  8 15:05 io
-r--r--r--. 1 root root 0 Sep  8 15:05 cpu

$cat /proc/pressure/memory 
some avg10=0.00 avg60=0.00 avg300=0.31 total=4121665
full avg10=0.00 avg60=0.00 avg300=0.06 total=1394483

sosreport-rh84-test-2021-09-08-abemgkl]# ls -lrt proc/pressure
ls: cannot access 'proc/pressure': No such file or directory

sos_commands]# find . -name pressure*
$