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.

       This tool uses the  irq:irq_handler_entry  and  irq:irq_handler_exit  kernel  tracepoints,
       which is a stable tracing mechanism. BPF programs can attach to tracepoints from Linux 4.7
       only. An older version of this tool is available in tools/old, and uses kprobes instead of
       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.

       -c CPU Trace on this CPU only.

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

       Sum hard IRQ event time on CPU 1 until Ctrl-C:
              # hardirqs -c 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, Hengqi Chen, Rocky Xing

SEE ALSO

       softirqs(8)