Provided by: bpfcc-tools_0.18.0+ds-2_all
nfsdist - Summarize NFS operation latency. Uses Linux eBPF/bcc.
nfsdist [-h] [-T] [-m] [-p PID] [interval] [count]
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.
CONFIG_BPF and bcc.
-h Print usage message. -T Don't include timestamps on interval output. -m Output in milliseconds. -p PID Trace this PID only.
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
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).
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.
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.
Unstable - in development.