biostacks - Show disk I/O latency with initialization stacks. Uses bpftrace/eBPF.

       Brendan Gregg

       This  tool shows disk I/O latency histograms for each block I/O initialization path. This can help reveal
       the reason for different latencies, as some may be created by log flushing, others by application  reads,
       etc.

       This works by attaching to block_io_start and block_rq_issue tracepoints.

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

       Trace disk I/O latency with initialization stacks:
              # biostacks.bt

       0th    An initialization kernel stack trace (shown in "@[...]") is printed before each I/O histogram.

       1st, 2nd
              This is a range of I/O latency, in microseconds (shown in "[...)" set notation).

       3rd    A column showing the count of I/O in this range.

       4th    This is an ASCII histogram representing the count column.

       biostacks - Show disk I/O latency with initialization stacks. Uses bpftrace/eBPF.

       Linux

       The  rate  of  biostacks  should  be low (bounded by device IOPS), such that the overhead of this tool is
       expected to be negligible.

       CONFIG_BPF and bpftrace.

biosnoop.bt(8)

USER COMMANDS                                      2019-07-12                                    biostacks.bt(8)

       This tool originated from the book "BPF Performance Tools", published by Addison Wesley (2019):

              http://www.brendangregg.com/bpf-performance-tools-book.html

       See the book for more documentation on this tool.

       This version is in the bpftrace repository:

              https://github.com/bpftrace/bpftrace

       Also look in the bpftrace distribution for a  companion  _examples.txt  file  containing  example  usage,
       output, and commentary for this tool.

       Unstable - in development.

biostacks