nfsdist(8) System Manager's Manual nfsdist(8)

# [NAME](#NAME)

nfsdist - Summarize NFS operation latency. Uses Linux eBPF/bcc.

# [SYNOPSIS](#SYNOPSIS)

**nfsdist \[-h] \[-T] \[-m] \[-p PID] \[interval] \[count]**

# [DESCRIPTION](#DESCRIPTION)

This tool summarizes time (latency) spent in common NFS file operations: reads, writes, opens, and getattrs, and presents it as a power-of-2 histogram. It uses an in-kernel eBPF map to store the histogram for efficiency.

Since this works by tracing the nfs\_file\_operations interface functions, it will need updating to match any changes to these functions.

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

# [REQUIREMENTS](#REQUIREMENTS)

CONFIG\_BPF and bcc.

# [OPTIONS](#OPTIONS)

[-h](#h)

Print usage message.

[-T](#T)

Don't include timestamps on interval output.

[-m](#m)

Output in milliseconds.

[-p PID](#p)

Trace this PID only.

# [EXAMPLES](#EXAMPLES)

[Trace NFS operation time, and print a summary on Ctrl-C:](#Trace)

\# **nfsdist**

[Trace PID 181 only:](#Trace~2)

\# **nfsdist -p 181**

[Print 1 second summaries, 10 times:](#Print)

\# **nfsdist 1 10**

1 second summaries, printed in milliseconds

\# **nfsdist -m 1**

# [FIELDS](#FIELDS)

[msecs](#msecs)

Range of milliseconds for this bucket.

[usecs](#usecs)

Range of microseconds for this bucket.

[count](#count)

Number of operations in this time range.

[distribution](#distribution)

ASCII representation of the distribution (the count column).

# [OVERHEAD](#OVERHEAD)

This adds low-overhead instrumentation to these NFS operations, including reads and writes from the file system cache. Such reads and writes can be very frequent (depending on the workload; eg, 1M/sec), at which point the overhead of this tool may become noticeable. Measure and quantify before use.

# [SOURCE](#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](#OS)

Linux

# [STABILITY](#STABILITY)

Unstable - in development.

# [AUTHOR](#AUTHOR)

Samuel Nair

# [SEE ALSO](#SEE_ALSO)

[nfsslower(8)](/man/enterprise-packages/bcc/nfsslower.8)

2017-09-08 USER COMMANDS

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Document: nfsdist(8) from bcc 0.37.0-r3 (Chainguard OS)
Source: https://github.com/iovisor/bcc