NAME

       softirqs - Measure soft IRQ (soft interrupt) event time. Uses Linux eBPF/bcc.

SYNOPSIS

       softirqs [-h] [-T] [-N] [-C] [-d] [-c CPU] [interval] [count]

DESCRIPTION

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

       This tool uses the irq:softirq_enter and irq:softirq_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     Show the number of soft irq events.

       -d     Show IRQ time distribution as histograms.

       -c CPU Trace on this CPU only.

EXAMPLES

       Sum soft IRQ event time until Ctrl-C:
              # softirqs

       Show the number of soft irq events:
              # softirqs -C

       Show soft IRQ event time as histograms:
              # softirqs -d

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

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

       Sum soft IRQ event time on CPU 1 until Ctrl-C:
              # softirqs -c 1

FIELDS

       SOFTIRQ
              The kernel function name that performs the soft IRQ action.

       TOTAL_usecs
              Total time spent in this soft IRQ function in microseconds.

       TOTAL_nsecs
              Total time spent in this soft IRQ function in nanoseconds.

       usecs  Range of microseconds for this bucket.

       nsecs  Range of nanoseconds for this bucket.

       count  Number of soft 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.

AUTHORS

       Brendan Gregg, Sasha Goldshtein, Rocky Xing

SEE ALSO

       hardirqs(8)