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)