nfsdist(8) System Manager's Manual nfsdist(8)
NAME
nfsdist - Summarize NFS operation latency. Uses Linux eBPF/bcc.
SYNOPSIS
nfsdist [-h] [-T] [-m] [-p PID] [interval] [count]
DESCRIPTION
This tool summarizes time (latency) spent in common NFS file opera-
tions: 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 func-
tions, it will need updating to match any changes to these functions.
Since this uses BPF, only the root user can use this tool.
REQUIREMENTS
CONFIG_BPF and bcc.
OPTIONS
-h Print usage message.
-T Don't include timestamps on interval output.
-m Output in milliseconds.
-p PID Trace this PID only.
EXAMPLES
Trace NFS operation time, and print a summary on Ctrl-C:
# nfsdist
Trace PID 181 only:
# nfsdist -p 181
Print 1 second summaries, 10 times:
# nfsdist 1 10
1 second summaries, printed in milliseconds
# nfsdist -m 1
FIELDS
msecs Range of milliseconds for this bucket.
usecs Range of microseconds for this bucket.
count Number of operations in this time range.
distribution
ASCII representation of the distribution (the count column).
OVERHEAD
This adds low-overhead instrumentation to these NFS operations, includ-
ing 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
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
Samuel Nair
SEE ALSO
nfsslower(8)
USER COMMANDS 2017-09-08 nfsdist(8)
Generated by dwww version 1.16 on Tue Dec 16 05:46:55 CET 2025.