---
name: "cpudist-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/cpudist-bpfcc"
---

# cpudist-bpfcc(8)

On- and off-CPU task time as a histogram.

## NAME

cpudist - On- and off-CPU task time as a histogram.

## SYNOPSIS

**cpudist \[-h\] \[-O\] \[-T\] \[-m\] \[-P\] \[-L\] \[-p PID\] \[-I\] \[-e\] \[interval\] \[count\]**

## DESCRIPTION

This measures the time a task spends on the CPU before being descheduled, and shows the times as a histogram. Tasks that spend a very short time on the CPU can be indicative of excessive context-switches and poor workload distribution, and possibly point to a shared source of contention that keeps tasks switching in and out as it becomes available (such as a mutex).

Similarly, the tool can also measure the time a task spends off-CPU before it is scheduled again. This can be helpful in identifying long blocking and I/O operations, or alternatively very short descheduling times due to short-lived locks or timers.

By default CPU idle time are excluded by simply excluding PID 0.

This tool uses in-kernel eBPF maps for storing timestamps and the histogram, for efficiency. Despite this, the overhead of this tool may become significant for some workloads: see the OVERHEAD section.

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

## REQUIREMENTS

CONFIG\_BPF and bcc.

## OPTIONS

- \-h

  Print usage message.

- \-O

  Measure off-CPU time instead of on-CPU time.

- \-T

  Include timestamps on output.

- \-m

  Output histogram in milliseconds.

- \-P

  Print a histogram for each PID (tgid from the kernel's perspective).

- \-L

  Print a histogram for each TID (pid from the kernel's perspective).

- \-p PID

  Only show this PID (filtered in kernel for efficiency).

- \-I

  Include CPU idle time (by default these are excluded).

- \-e

  Show extension summary (average/total/count).

- interval

  Output interval, in seconds.

- count

  Number of outputs.

## EXAMPLES

- Summarize task on-CPU time as a histogram:

  \# **cpudist**

- Summarize task off-CPU time as a histogram:

  \# **cpudist -O**

- Print 1 second summaries, 10 times:

  \# **cpudist 1 10**

- Print 1 second summaries, using milliseconds as units for the histogram, and include timestamps on output:

  \# **cpudist -mT 1**

- Trace PID 185 only, 1 second summaries:

  \# **cpudist -p 185 1**

- Include CPU idle time:

  \# **cpudist -I**

- Also show extension summary:

  \# **cpudist -e**

## FIELDS

- usecs

  Microsecond range

- msecs

  Millisecond range

- count

  How many times a task event fell into this range

- distribution

  An ASCII bar chart to visualize the distribution (count column)

## OVERHEAD

This traces scheduler tracepoints, which can become very frequent. While eBPF has very low overhead, and this tool uses in-kernel maps for efficiency, the frequency of scheduler events for some workloads may be high enough that the overhead of this tool becomes significant. Measure in a lab environment to quantify the overhead before use.

## SOURCE

This is from bcc.

-

  https://github.com/iovisor/bcc

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

## OS

Linux

## STABILITY

Unstable - in development.

## AUTHOR

Sasha Goldshtein, Rocky Xing

## SEE ALSO

[pidstat(1)](/pidstat/1.md), runqlat(8)