swapin.bt(8)

1swapin.bt(8)                System Manager's Manual               swapin.bt(8)
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NAME

6       swapin.bt - Count swapins by process. Uses bpftrace/eBPF.
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SYNOPSIS

9       swapin
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DESCRIPTION

12       This  tool counts swapins by process, to show which process is affected
13       by swapping (if swap devices are in use). This can explain  a  signifi‐
14       cant  source  of  application  latency, if it has began swapping due to
15       memory pressure on the system.
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17       This works by tracing the swap_readpage() kernel function using dynamic
18       instrumentation. This tool may need maintenance to keep working if that
19       function changes in later kernels.
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21       Since this uses BPF, only the root user can use this tool.
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REQUIREMENTS

24       CONFIG_BPF and bpftrace.
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EXAMPLES

27       Count swapins by process, showing per-second summaries.
28              # swapin.bt
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FIELDS

31       1st    The process name.
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33       2nd    The process ID.
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35       3rd    The count of swapins during that interval.
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OVERHEAD

38       The rate of swapins should be low (bounded by swapin device IOPS), such
39       that the overhead of this tool is expected to be negligible.
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SOURCE

42       This  tool  originated from the book "BPF Performance Tools", published
43       by Addison Wesley (2019):
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45              http://www.brendangregg.com/bpf-performance-tools-book.html
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47       See the book for more documentation on this tool.
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49       This version is in the bpftrace repository:
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51              https://github.com/iovisor/bpftrace
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53       Also look in the bpftrace distribution for  a  companion  _examples.txt
54       file containing example usage, output, and commentary for this tool.
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OS

57       Linux
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STABILITY

60       Unstable - in development.
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AUTHOR

63       Brendan Gregg
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