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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | START COMMAND | STOP COMMAND | SIGNAL COMMAND | PING COMMAND | CONFIG FILE | EXAMPLES | SEE ALSO | COLOPHON |
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PERF-DAEMON(1) perf Manual PERF-DAEMON(1)
perf-daemon - Run record sessions on background
perf daemon
perf daemon [<options>]
perf daemon start [<options>]
perf daemon stop [<options>]
perf daemon signal [<options>]
perf daemon ping [<options>]
This command allows to run simple daemon process that starts and
monitors configured record sessions.
You can imagine perf daemon of background process with several
perf record child tasks, like:
# ps axjf
...
1 916507 ... perf daemon start
916507 916508 ... \_ perf record --control=fifo:control,ack -m 10M -e cycles --overwrite --switch-output -a
916507 916509 ... \_ perf record --control=fifo:control,ack -m 20M -e sched:* --overwrite --switch-output -a
Not every perf record session is suitable for running under
daemon. User need perf session that either produces data on query,
like the flight recorder sessions in above example or session that
is configured to produce data periodically, like with
--switch-output configuration for time and size.
Each session is started with control setup (with perf record
--control options).
Sessions are configured through config file, see CONFIG FILE
section with EXAMPLES.
-v, --verbose
Be more verbose.
--config=<PATH>
Config file path. If not provided, perf will check system and
default locations (/etc/perfconfig, $HOME/.perfconfig).
--base=<PATH>
Base directory path. Each daemon instance is running on top of
base directory. Only one instance of server can run on top of
one directory at the time.
All generic options are available also under commands.
The start command creates the daemon process.
-f, --foreground
Do not put the process in background.
The stop command stops all the session and the daemon process.
The signal command sends signal to configured sessions.
--session
Send signal to specific session.
The ping command sends control ping to configured sessions.
--session
Send ping to specific session.
The daemon is configured within standard perf config file by
following new variables:
daemon.base: Base path for daemon data. All sessions data are
stored under this path.
session-<NAME>.run: Defines new record session. The value is
record’s command line without the record keyword.
Each perf record session is run in daemon.base/<NAME> directory.
Example with 2 record sessions:
# cat ~/.perfconfig
[daemon]
base=/opt/perfdata
[session-cycles]
run = -m 10M -e cycles --overwrite --switch-output -a
[session-sched]
run = -m 20M -e sched:* --overwrite --switch-output -a
Starting the daemon:
# perf daemon start
Check sessions:
# perf daemon
[603349:daemon] base: /opt/perfdata
[603350:cycles] perf record -m 10M -e cycles --overwrite --switch-output -a
[603351:sched] perf record -m 20M -e sched:* --overwrite --switch-output -a
First line is daemon process info with configured daemon base.
Check sessions with more info:
# perf daemon -v
[603349:daemon] base: /opt/perfdata
output: /opt/perfdata/output
lock: /opt/perfdata/lock
up: 1 minutes
[603350:cycles] perf record -m 10M -e cycles --overwrite --switch-output -a
base: /opt/perfdata/session-cycles
output: /opt/perfdata/session-cycles/output
control: /opt/perfdata/session-cycles/control
ack: /opt/perfdata/session-cycles/ack
up: 1 minutes
[603351:sched] perf record -m 20M -e sched:* --overwrite --switch-output -a
base: /opt/perfdata/session-sched
output: /opt/perfdata/session-sched/output
control: /opt/perfdata/session-sched/control
ack: /opt/perfdata/session-sched/ack
up: 1 minutes
The base path is daemon/session base. The lock file is daemon’s
lock file guarding that no other daemon is running on top of the
base. The output file is perf record output for specific session.
The control and ack files are perf control files. The up number
shows minutes daemon/session is running.
Make sure control session is online:
# perf daemon ping
OK cycles
OK sched
Send USR2 signal to session cycles to generate perf.data file:
# perf daemon signal --session cycles
signal 12 sent to session 'cycles [603452]'
# tail -2 /opt/perfdata/session-cycles/output
[ perf record: dump data: Woken up 1 times ]
[ perf record: Dump perf.data.2020123017013149 ]
Send USR2 signal to all sessions:
# perf daemon signal
signal 12 sent to session 'cycles [603452]'
signal 12 sent to session 'sched [603453]'
# tail -2 /opt/perfdata/session-cycles/output
[ perf record: dump data: Woken up 1 times ]
[ perf record: Dump perf.data.2020123017024689 ]
# tail -2 /opt/perfdata/session-sched/output
[ perf record: dump data: Woken up 1 times ]
[ perf record: Dump perf.data.2020123017024713 ]
Stop daemon:
# perf daemon stop
perf-record(1), perf-config(1)
This page is part of the perf (Performance analysis tools for
Linux (in Linux source tree)) project. Information about the
project can be found at
⟨https://perf.wiki.kernel.org/index.php/Main_Page⟩. If you have a
bug report for this manual page, send it to
linux-kernel@vger.kernel.org. This page was obtained from the
project's upstream Git repository
⟨http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git⟩
on 2025-08-11. (At that time, the date of the most recent commit
that was found in the repository was 2025-08-10.) If you discover
any rendering problems in this HTML version of the page, or you
believe there is a better or more up-to-date source for the page,
or you have corrections or improvements to the information in this
COLOPHON (which is not part of the original manual page), send a
mail to man-pages@man7.org
perf 2021-02-11 PERF-DAEMON(1)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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