Re: iocStats CPU time seems wrong

[Mark Rivers via Tech-talk <tech-talk at aps.anl.gov>]

Folks,

Looking at the code, the IOC_CPU_LOAD is indeed in units of % of all CPUs, not % of a single CPU which is what the label in the OPI screen says.

I have created a PR: https://github.com/epics-modules/iocStats/pull/85

It creates a new record IOC_SINGLE_CPU_LOAD, and uses this record in the OPI screens to agree with the label.

It also adds new records for memory statistics that are in units of GB, rather than bytes.  These are much easier to read on systems with lots of memory.

Mark

---

From: Mark Rivers <rivers at cars.uchicago.edu>
Sent: Sunday, May 31, 2026 1:28 PM
To: tech-talk <tech-talk at aps.anl.gov>
Subject: iocStats CPU time seems wrong

Folks,

I have an areaDetector IOC running spinnakerApp that is using ~27% of  CPU on Linux according to "top".  I have attached a screenshot of "top".

The IOC is running iocStats.  I am using the current master branch of iocStats.  The problem is that iocStats reports IOC_CPU_LOAD is 0.8% (see attached screenshot).  The label on the OPI screen says that means % of a single CPU, which is what "top" is also showing.

Why are these so different?  Is IOC_CPU_LOAD really not in units of one CPU, but in units of all CPUs?

Thanks,

Mark