59 lines
1.5 KiB
Groff
59 lines
1.5 KiB
Groff
.TH swapin 8 "2019-07-05" "USER COMMANDS"
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.SH NAME
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swapin \- Count swapins by process. Uses BCC/eBPF.
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.SH SYNOPSIS
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.B swapin
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.SH DESCRIPTION
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This tool counts swapins by process, to show which process is affected by
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swapping (if swap devices are in use). This can explain a significant source
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of application latency, if it has began swapping due to memory pressure on
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the system.
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This works by tracing the swap_readpage() kernel funciton
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using dynamic instrumentation. This tool may need maintenance to keep working
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if that function changes in later kernels.
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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 EXAMPLES
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.TP
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Count swapins by process, showing per-second summaries.
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#
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.B swapin
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.SH FIELDS
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.TP
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1st
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The process name.
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.TP
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2nd
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The process ID.
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.TP
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3rd
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The count of swapins during that interval.
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.SH OVERHEAD
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The rate of swapins should be low (bounded by swapin device IOPS), such that
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the overhead of this tool is expected to be negligible.
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.SH SOURCE
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This originated as a bpftrace tool from the book "BPF Performance Tools",
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published by Addison Wesley (2019):
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.IP
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http://www.brendangregg.com/bpf-performance-tools-book.html
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.PP
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See the book for more documentation on this tool.
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.PP
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This version is in the BCC repository:
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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
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containing 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 AUTHOR
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Brendan Gregg
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.SH SEE ALSO
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swapon(8)
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