|hardirqs(8)||System Manager's Manual||hardirqs(8)|
hardirqs - Measure hard IRQ (hard interrupt) event time. Uses Linux eBPF/bcc.
hardirqs [-h] [-T] [-N] [-C] [-d] [interval] [outputs]
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.
CONFIG_BPF and bcc.
- The irq action name for this hard IRQ.
- Total time spent in this hard IRQ in microseconds.
- Total time spent in this hard IRQ in nanoseconds.
- Range of microseconds for this bucket.
- Range of nanoseconds for this bucket.
- Number of hard IRQs in this time range.
- ASCII representation of the distribution (the count column).
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.
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.
Unstable - in development.
Brendan Gregg, Hengqi Chen