---
name: "cachetop-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/cachetop-bpfcc"
---

# cachetop-bpfcc(8)

Statistics for linux page cache hit/miss ratios per processes. Uses Linux eBPF/bcc.

## NAME

cachetop - Statistics for linux page cache hit/miss ratios per processes. Uses Linux eBPF/bcc.

## SYNOPSIS

**cachetop \[-p PID\]** \[interval\]

## DESCRIPTION

This traces four kernel functions and prints per-processes summaries every **interval** seconds. This can be useful for processes workload characterization, and looking for patterns in operation usage over time. It provides a **top**-like interface which by default sorts by **HITS** in ascending order.

This works by tracing kernel page cache functions using dynamic tracing, and will need updating to match any changes to these functions. Edit the script to customize which functions are traced.

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

## OPTIONS

- \-p PID

  Trace this PID only.

## KEYBINDINGS

The following keybindings can be used to control the output of **cachetop**.

- **\<**

  Use the previous column for sorting.

- **\>**

  Use the next column for sorting.

- **r**

  Toggle sorting order (default ascending).

- **q**

  Quit cachetop.

## REQUIREMENTS

CONFIG\_BPF and bcc.

## EXAMPLES

- Update summaries every five second:

  \# **cachetop**

- Print summaries each second:

  \# **cachetop 1**

## FIELDS

- PID

  Process ID of the process causing the cache activity.

- UID

  User ID of the process causing the cache activity.

- CMD

  Name of the process.

- HITS

  Number of page cache hits.

- MISSES

  Number of page cache misses.

- DIRTIES

  Number of dirty pages added to the page cache.

- READ\_HIT%

  Read hit percent of page cache usage.

- WRITE\_HIT%

  Write hit percent of page cache usage.

- BUFFERS\_MB

  Buffers size taken from /proc/meminfo.

- CACHED\_MB

  Cached amount of data in current page cache taken from /proc/meminfo.

## OVERHEAD

This traces various kernel page cache functions and maintains in-kernel counts, which are asynchronously copied to user-space. While the rate of operations can be very high (\>1G/sec) we can have up to 34% overhead, this is still a relatively efficient way to trace these events, and so the overhead is expected to be small for normal workloads. Measure in a test environment.

## 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

Emmanuel Bretelle, Rocky Xing

## SEE ALSO

cachestat (8)