drsnoop-bpfcc(8)

Usage

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

Overview

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.

Releases

3 releases since Debian 11 (Bullseye); the text changed 1 time.

11
12–13

-v since Debian 12 (Bookworm).