NAME

       hardirqs - Measure hard IRQ (hard interrupt) event time. Uses Linux eBPF/bcc.

SYNOPSIS

       hardirqs [-h] [-T] [-N] [-C] [-d] [interval] [outputs]

DESCRIPTION

       This  summarizes  the  time spent servicing hard IRQs (hard interrupts), and can show this time as either
       totals or histogram distributions. A system-wide summary of this time is shown  by  the  %irq  column  of
       mpstat(1), and event counts (but not times) are shown by /proc/interrupts.

       WARNING:  This  currently  uses dynamic tracing of hard interrupts. You should understand what this means
       before use. Try in a test environment. Future versions should switch to tracepoints.

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

REQUIREMENTS

       CONFIG_BPF and bcc.

OPTIONS

       -h     Print usage message.

       -T     Include timestamps on output.

       -N     Output in nanoseconds.

       -C     Count events only.

       -d     Show IRQ time distribution as histograms.

EXAMPLES

       Sum hard IRQ event time until Ctrl-C:
              # hardirqs

       Show hard IRQ event time as histograms:
              # hardirqs -d

       Print 1 second summaries, 10 times:
              # hardirqs 1 10

       1 second summaries, printed in nanoseconds, with timestamps:
              # hardirqs -NT 1

FIELDS

       HARDIRQ
              The irq action name for this hard IRQ.

       TOTAL_usecs
              Total time spent in this hard IRQ in microseconds.

       TOTAL_nsecs
              Total time spent in this hard IRQ in nanoseconds.

       usecs  Range of microseconds for this bucket.

       nsecs  Range of nanoseconds for this bucket.

       count  Number of hard IRQs in this time range.

       distribution
              ASCII representation of the distribution (the count column).

OVERHEAD

       This traces kernel functions and maintains in-kernel counts, which are  asynchronously  copied  to  user-
       space.  While  the rate of interrupts be very high (>1M/sec), this is a relatively efficient way to trace
       these events, and so the overhead is expected  to  be  small  for  normal  workloads,  but  could  become
       noticeable for heavy workloads. Measure in a test environment 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

       Brendan Gregg

SEE ALSO

       softirqs(8)

USER COMMANDS                                      2015-10-20                                        hardirqs(8)