---
name: "hardirqs-bpfcc"
section: "8"
platform: "linux"
package: "bpfcc-tools"
version: "0.31.0+ds-7"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/hardirqs-bpfcc"
---

# hardirqs-bpfcc(8)

Measure hard IRQ (hard interrupt) event time. Uses Linux eBPF/bcc.

## NAME

hardirqs - Measure hard IRQ (hard interrupt) event time. Uses Linux eBPF/bcc.

## SYNOPSIS

**hardirqs \[-h\] \[-T\] \[-N\] \[-C\] \[-d\] \[interval\] \[outputs\]**

## DESCRIPTION

This summarizes the time spent servicing hard IRQs (hard interrupts), and can show this time as either totals or histogram distributions. A system-wide summary of this time is shown by the %irq column of [mpstat(1)](/mpstat/1.md), and event counts (but not times) are shown by /proc/interrupts.

This tool uses the irq:irq\_handler\_entry and irq:irq\_handler\_exit kernel tracepoints, which is a stable tracing mechanism. BPF programs can attach to tracepoints from Linux 4.7 only. An older version of this tool is available in tools/old, and uses kprobes instead of tracepoints.

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

## REQUIREMENTS

CONFIG\_BPF and bcc.

## OPTIONS

- \-h

  Print usage message.

- \-T

  Include timestamps on output.

- \-N

  Output in nanoseconds.

- \-C

  Count events only.

- \-d

  Show IRQ time distribution as histograms.

- \-c CPU

  Trace on this CPU only.

## EXAMPLES

- Sum hard IRQ event time until Ctrl-C:

  \# **hardirqs**

- Show hard IRQ event time as histograms:

  \# **hardirqs -d**

- Print 1 second summaries, 10 times:

  \# **hardirqs 1 10**

- 1 second summaries, printed in nanoseconds, with timestamps:

  \# **hardirqs -NT 1**

- Sum hard IRQ event time on CPU 1 until Ctrl-C:

  \# **hardirqs -c 1**

## FIELDS

- HARDIRQ

  The irq action name for this hard IRQ.

- TOTAL\_usecs

  Total time spent in this hard IRQ in microseconds.

- TOTAL\_nsecs

  Total time spent in this hard IRQ in nanoseconds.

- usecs

  Range of microseconds for this bucket.

- nsecs

  Range of nanoseconds for this bucket.

- count

  Number of hard IRQs in this time range.

- distribution

  ASCII representation of the distribution (the count column).

## OVERHEAD

This traces kernel functions and maintains in-kernel counts, which are asynchronously copied to user-space. While the rate of interrupts be very high (\>1M/sec), this is a relatively efficient way to trace these events, and so the overhead is expected to be small for normal workloads, but could become noticeable for heavy workloads. Measure in a test environment before use.

## SOURCE

This is from bcc.

-

  https://github.com/iovisor/bcc

Also look in the bcc 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, Hengqi Chen, Rocky Xing

## SEE ALSO

softirqs(8)