| .TH hardirqs 8 "2015-10-20" "USER COMMANDS" |
| .SH NAME |
| hardirqs \- Measure hard IRQ (hard interrupt) event time. Uses Linux eBPF/bcc. |
| .SH SYNOPSIS |
| .B hardirqs [\-h] [\-T] [\-N] [\-C] [\-d] [interval] [outputs] |
| .SH 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. |
| .SH REQUIREMENTS |
| CONFIG_BPF and bcc. |
| .SH OPTIONS |
| .TP |
| \-h |
| Print usage message. |
| .TP |
| \-T |
| Include timestamps on output. |
| .TP |
| \-N |
| Output in nanoseconds. |
| .TP |
| \-C |
| Count events only. |
| .TP |
| \-d |
| Show IRQ time distribution as histograms. |
| .SH EXAMPLES |
| .TP |
| Sum hard IRQ event time until Ctrl-C: |
| # |
| .B hardirqs |
| .TP |
| Show hard IRQ event time as histograms: |
| # |
| .B hardirqs \-d |
| .TP |
| Print 1 second summaries, 10 times: |
| # |
| .B hardirqs 1 10 |
| .TP |
| 1 second summaries, printed in nanoseconds, with timestamps: |
| # |
| .B hardirqs \-NT 1 |
| .SH FIELDS |
| .TP |
| HARDIRQ |
| The irq action name for this hard IRQ. |
| .TP |
| TOTAL_usecs |
| Total time spent in this hard IRQ in microseconds. |
| .TP |
| TOTAL_nsecs |
| Total time spent in this hard IRQ in nanoseconds. |
| .TP |
| usecs |
| Range of microseconds for this bucket. |
| .TP |
| nsecs |
| Range of nanoseconds for this bucket. |
| .TP |
| count |
| Number of hard IRQs in this time range. |
| .TP |
| distribution |
| ASCII representation of the distribution (the count column). |
| .SH 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. |
| .SH SOURCE |
| This is from bcc. |
| .IP |
| https://github.com/iovisor/bcc |
| .PP |
| Also look in the bcc distribution for a companion _examples.txt file containing |
| example usage, output, and commentary for this tool. |
| .SH OS |
| Linux |
| .SH STABILITY |
| Unstable - in development. |
| .SH AUTHOR |
| Brendan Gregg, Hengqi Chen |
| .SH SEE ALSO |
| softirqs(8) |
