Manual: softirqs-bpfcc

softirqs(8)				   System Manager's Manual				 softirqs(8)

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 ei‐
       ther totals or histogram distributions. A system-wide summary of this time is shown by the %soft col‐
       umn 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 trac‐
       ing 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	 be‐
       come 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, out‐
       put, and commentary for this tool.

OS
       Linux

STABILITY
       Unstable - in development.

AUTHORS
       Brendan Gregg, Sasha Goldshtein, Rocky Xing

SEE ALSO
       hardirqs(8)

USER COMMANDS					 2015-10-20					 softirqs(8)