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94 lines
2.4 KiB
94 lines
2.4 KiB
.TH softirqs 8 "2015-10-20" "USER COMMANDS"
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.SH NAME
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softirqs \- Measure soft IRQ (soft interrupt) event time. Uses Linux eBPF/bcc.
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.SH SYNOPSIS
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.B softirqs [\-h] [\-T] [\-N] [\-d] [interval] [count]
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.SH DESCRIPTION
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This summarizes the time spent servicing soft IRQs (soft interrupts), and can
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show this time as either totals or histogram distributions. A system-wide
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summary of this time is shown by the %soft column of mpstat(1), and soft IRQ
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event counts (but not times) are available in /proc/softirqs.
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This tool uses the irq:softirq_enter and irq:softirq_exit kernel tracepoints,
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which is a stable tracing mechanism. BPF programs can attach to tracepoints
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from Linux 4.7 only. An older version of this tool is available in tools/old,
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and uses kprobes instead of tracepoints.
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Since this uses BPF, only the root user can use this tool.
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.SH REQUIREMENTS
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CONFIG_BPF and bcc.
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.SH OPTIONS
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.TP
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\-h
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Print usage message.
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.TP
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\-T
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Include timestamps on output.
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.TP
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\-N
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Output in nanoseconds
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.TP
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\-d
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Show IRQ time distribution as histograms
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.SH EXAMPLES
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.TP
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Sum soft IRQ event time until Ctrl-C:
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#
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.B softirqs
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.TP
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Show soft IRQ event time as histograms:
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#
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.B softirqs \-d
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.TP
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Print 1 second summaries, 10 times:
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#
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.B softirqs 1 10
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.TP
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1 second summaries, printed in nanoseconds, with timestamps:
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#
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.B softirqs \-NT 1
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.SH FIELDS
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.TP
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SOFTIRQ
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The kernel function name that performs the soft IRQ action.
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.TP
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TOTAL_usecs
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Total time spent in this soft IRQ function in microseconds.
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.TP
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TOTAL_nsecs
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Total time spent in this soft IRQ function in nanoseconds.
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.TP
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usecs
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Range of microseconds for this bucket.
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.TP
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nsecs
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Range of nanoseconds for this bucket.
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.TP
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count
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Number of soft IRQs in this time range.
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.TP
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distribution
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ASCII representation of the distribution (the count column).
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.SH OVERHEAD
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This traces kernel functions and maintains in-kernel counts, which
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are asynchronously copied to user-space. While the rate of interrupts
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be very high (>1M/sec), this is a relatively efficient way to trace these
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events, and so the overhead is expected to be small for normal workloads, but
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could become noticeable for heavy workloads. Measure in a test environment
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before use.
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.SH SOURCE
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This is from bcc.
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.IP
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https://github.com/iovisor/bcc
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.PP
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Also look in the bcc distribution for a companion _examples.txt file containing
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example usage, output, and commentary for this tool.
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.SH OS
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Linux
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.SH STABILITY
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Unstable - in development.
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.SH AUTHORS
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Brendan Gregg, Sasha Goldshtein
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.SH SEE ALSO
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hardirqs(8)
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