|softirqs(8)||System Manager's Manual||softirqs(8)|
softirqs - Measure soft IRQ (soft interrupt) event time. Uses Linux eBPF/bcc.
softirqs [-h] [-T] [-N] [-C] [-d] [-c CPU] [interval] [count]
This summarizes the time spent servicing soft IRQs (soft interrupts), and can show this time as either totals or histogram distributions. A system-wide summary of this time is shown by the %soft column 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 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.
- 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
- The kernel function name that performs the soft IRQ action.
- Total time spent in this soft IRQ function in microseconds.
- Total time spent in this soft IRQ function in nanoseconds.
- Range of microseconds for this bucket.
- Range of nanoseconds for this bucket.
- Number of soft 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, Sasha Goldshtein, Rocky Xing