dwww: tpablo.net

PERF-DAEMON(1) perf Manual PERF-DAEMON(1)

NAME
perf-daemon - Run record sessions on background

SYNOPSIS
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