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 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

       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, 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

       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)