Command "lparstat -E" is failing to open files

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Environment

SUSE Linux Enterprise Server 15 SP4

Situation

When performing a "lparstat -E" the following error message (as it happens today) is being displayed:

$ lparstat -E
Failed to open /sys/devices/system/cpu/cpu340/idle_purr

Resolution

As a workaround for this issue, increase the maximum number of open file descriptors using "ulimit -n" as shown below:

$ nproc
480

Number of file descriptors needed is (480 * 3) + 10, which is 1450.

$ ulimit -n 1450

Alternatively, increase the limit to a higher value like 30k below

$ ulimit -n 30000

Cause

On max config system, "lparstat -E" option is failing to open a few files even though they are present. This is because the number of open file descriptors for a Linux user process is limited to 1024 by default. But, lparstat requires more than (nproc * 3) file descriptors to be able to open all the files and for "lparstat -E" to work.

Disclaimer

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