drsnoop(8)

NAME
drsnoop - Trace direct reclaim events. Uses Linux eBPF/bcc.

SYNOPSIS
drsnoop [-h] [-T] [-U] [-p PID] [-t TID] [-u UID] [-d DURATION] [-n name] [-v]

DESCRIPTION
drsnoop trace direct reclaim events, showing which processes are allocing pages with direct reclaiming. This can be useful for discovering when allocstall (/p- roc/vmstat) continues to increase, whether it is caused by some critical proc- esses or not.

This works by tracing the direct reclaim events using kernel tracepoints.

This makes use of a Linux 4.4 feature (bpf_perf_event_output()); for kernels older than 4.4, see the version under tools/old, which uses an older mechanism.

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

REQUIREMENTS
CONFIG_BPF and bcc.

OPTIONS

-h  Print usage message.

-T  Include a timestamp column.

-U  Show UID.

-p PID
    Trace this process ID only (filtered in-kernel).

-t TID
    Trace this thread ID only (filtered in-kernel).

-u UID
    Trace this UID only (filtered in-kernel).

-d DURATION
    Total duration of trace in seconds.

-n name
    Only print processes where its name partially matches 'name' -v verbose Run in verbose mode. Will output system memory state

-v  show system memory state

EXAMPLES

Trace all direct reclaim events:
    # drsnoop

Trace all direct reclaim events, for 10 seconds only:
    # drsnoop -d 10

Trace all direct reclaim events, and include timestamps:
    # drsnoop -T

Show UID:
    # drsnoop -U

Trace PID 181 only:
    # drsnoop -p 181

Trace UID 1000 only:
    # drsnoop -u 1000

Trace all direct reclaim events from processes where its name partially match-
    es 'mond': # drnsnoop -n mond

FIELDS

TIME(s)
    Time of the call, in seconds.

UID User ID

PID Process ID

TID Thread ID

COMM
    Process name

OVERHEAD
This traces the kernel direct reclaim tracepoints and prints output for each event. As the rate of this is generally expected to be low (< 1000/s), the overhead is also expected to be negligible.

SOURCE
This is from bcc.

    https://github.com/iovisor/bcc

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

OS
Linux

STABILITY
Unstable - in development.

AUTHOR
Wenbo Zhang