hardirqs(8) System Manager's Manual hardirqs(8)
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 mp-
stat(1), and event counts (but not times) are shown by /proc/inter-
rupts.
This tool uses the irq:irq_handler_entry and irq:irq_handler_exit ker-
nel 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 trace-
points.
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 work-
loads, 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)
USER COMMANDS 2015-10-20 hardirqs(8)
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