NAME

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

SYNOPSIS

       swapin

DESCRIPTION

       This  tool  counts  swapins  by process, to show which process is affected by swapping (if
       swap devices are in use). This can explain a significant source of application latency, if
       it has began swapping due to memory pressure on the system.

       This  works  by tracing the swap_readpage() kernel function using dynamic instrumentation.
       This tool may need maintenance to keep working if that function changes in later kernels.

       Since this uses BPF, only the root user can use this tool.

REQUIREMENTS

       CONFIG_BPF and bpftrace.

EXAMPLES

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

FIELDS

       1st    The process name.

       2nd    The process ID.

       3rd    The count of swapins during that interval.

OVERHEAD

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

SOURCE

       This  tool  originated  from the book "BPF Performance Tools", published by Addison Wesley
       (2019):

              http://www.brendangregg.com/bpf-performance-tools-book.html

       See the book for more documentation on this tool.

       This version is in the bpftrace repository:

              https://github.com/iovisor/bpftrace

       Also look in the bpftrace distribution  for  a  companion  _examples.txt  file  containing
       example usage, output, and commentary for this tool.

OS

       Linux

STABILITY

       Unstable - in development.

AUTHOR

       Brendan Gregg

SEE ALSO

       swapon(8)