https://github.com/torvalds/linux
Tip revision: 03c765b0e3b4cb5063276b086c76f7a612856a9a authored by Linus Torvalds on 26 June 2022, 21:22:10 UTC
Linux 5.19-rc4
Linux 5.19-rc4
Tip revision: 03c765b
perf-daemon.txt
perf-daemon(1)
==============
NAME
----
perf-daemon - Run record sessions on background
SYNOPSIS
--------
[verse]
'perf daemon'
'perf daemon' [<options>]
'perf daemon start' [<options>]
'perf daemon stop' [<options>]
'perf daemon signal' [<options>]
'perf daemon ping' [<options>]
DESCRIPTION
-----------
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.
OPTIONS
-------
-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.
START COMMAND
-------------
The start command creates the daemon process.
-f::
--foreground::
Do not put the process in background.
STOP COMMAND
------------
The stop command stops all the session and the daemon process.
SIGNAL COMMAND
--------------
The signal command sends signal to configured sessions.
--session::
Send signal to specific session.
PING COMMAND
------------
The ping command sends control ping to configured sessions.
--session::
Send ping to specific session.
CONFIG FILE
-----------
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.
EXAMPLES
--------
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
SEE ALSO
--------
linkperf:perf-record[1], linkperf:perf-config[1]