NAME¶

cpuwalk.bt - Sample which CPUs are executing processes.. Uses bpftrace/eBPF.

SYNOPSIS¶

cpuwalk.bt

DESCRIPTION¶

This tool samples CPUs at 99 Hertz, then prints a histogram showing which CPUs were active. 99 Hertz is used to avoid lockstep sampling that would skew results. This tool can help identify if your application's workload is evenly using the CPUs, or if there is an imbalance problem.

Since this uses BPF, only the root user can use this tool.

REQUIREMENTS¶

CONFIG_BPF and bpftrace.

EXAMPLES¶

Sample CPUs and print a summary on Ctrl-C:

# cpuwalk.bt

FIELDS¶

1st, 2nd

The CPU is shown in the first field, after the "[". Disregard the second field.

3rd

A column showing the number of samples for this CPU.

4th

This is an ASCII histogram representing the count column.

OVERHEAD¶

This should be negligible.

SOURCE¶

This is from bpftrace.

https://github.com/iovisor/bpftrace

Also look in the bpftrace distribution for a companion _examples.txt file containing example usage, output, and commentary for this tool.

OS¶

Linux

STABILITY¶

Unstable - in development.

AUTHOR¶

Brendan Gregg

SEE ALSO¶

mpstat(1)