| 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 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¶
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.
Also look in the bcc distribution for a companion _examples.txt file containing example usage, output, and commentary for this tool.
OS¶
Linux
AUTHOR¶
Brendan Gregg, Hengqi Chen, Rocky Xing
SEE ALSO¶
softirqs(8)
| 2015-10-20 | USER COMMANDS |