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NAME | SYNOPSIS | DESCRIPTION | RUN MODES | OTHER OPTIONS | EXAMPLE | VERSION | SEE ALSO | COLOPHON |
OPERF(1) General Commands Manual OPERF(1)
operf - Performance profiler tool for Linux
operf [ options ] [ --system-wide | --pid <pid> | [ command [ args ]
] ]
Operf is the profiler tool provided with OProfile. Operf uses the
Linux Performance Events Subsystem and, thus, does not require the
obsolete oprofile kernel driver.
By default, operf uses <current_dir>/oprofile_data as the session-dir
and stores profiling data there. You can change this by way of the
--session-dir option. The usual post-profiling analysis tools such as
opreport(1) and opannotate(1) can be used to generate profile
reports. Unless a session-dir is specified, the post-processing
analysis tools will search for samples in <current_dir>/oprofile_data
first. If that directory does not exist, the post-processing tools
use the standard session-dir of /var/lib/oprofile.
Statistics, such as total samples received and lost samples, are
written to the operf.log file that can be found in the
<session_dir>/samples directory.
One (and only one) of the following run modes must be specified:
command[args]
The command or application to be profiled. args are the input
arguments that the command or application requires.
--pid / -p PID
This option enables operf to profile a running application.
PID should be the process ID of the process you wish to
profile. When finished profiling (e.g., when the profiled
process ends), press Ctrl-c to stop operf. If you run operf
--pid as a background job (i.e., with the &), you must stop it
in a controlled manner in order for it to process the profile
data it has collected. Use kill -SIGINT <operf-PID> for this
purpose.
Limitation: When using this option to profile a multi-threaded
application that also forks new processes, be aware that
samples for processes that are forked before profiling is
started may not be recorded (depending on timing of thread
creation and when operf is started).
--system-wide / -s
This option is for performing a system-wide profile. You must
have root authority to run operf in this mode. When finished
profiling, Ctrl-c to stop operf. If you run operf --system-
wide as a background job (i.e., with the &), you must stop it
in a controlled manner in order for it to process the profile
data it has collected. Use kill -SIGINT <operf-PID> for this
purpose. It is recommended that when running operf with this
option, the user's current working directory should be /root
or a subdirectory of /root to avoid storing sample data files
in locations accessible by regular users.
--vmlinux / -k vmlinux_path
A vmlinux file that matches the running kernel that has symbol
and/or debuginfo. Kernel samples will be attributed to this
binary, allowing post-processing tools (like opreport) to
attribute samples to the appropriate kernel symbols.
The kernel symbol information may be obtained from
/proc/kallsyms if the user does not specify a vmlinux file.
The symbol addresses are given in /proc/kallsyms if permitted
by the setting of /proc/sys/kernel/kptr_restrict.
If the --vmlinux option is not used and kernel symbols cannot
be obtained from /proc/kallsyms, then all kernel samples are
attributed to "no-vmlinux", which is simply a bucket to hold
the samples and not an actual file.
--events / -e event1[,event2[,...]]
This option is for passing a comma-separated list of event
specifications for profiling. Each event spec is of the form:
name:count[:unitmask[:kernel[:user]]]
The count value is used to control the sampling rate for
profiling; it is the number of events to occur between
samples. The rate is lowered by specifying a higher count
value — i.e., a higher number of events to occur between
samples.
You can specify unitmask values using either a numerical value
(hex values must begin with "0x") or a symbolic name (if the
name=<um_name> field is shown in the ophelp output). For some
named unit masks, the hex value is not unique; thus, OProfile
tools enforce specifying such unit masks value by name. If no
unit mask is specified, the default unit mask value for the
event is used.
The kernel and user parts of the event specification are
binary values ('1' or '0') indicating whether or not to
collect samples for kernel space and user space.
Note: In order to specify the kernel/user bits, you must also
specify a unitmask value, even if the processor type (or the
specified event) does not use unit masks — in which case, use
the value '0' to signify a null unit mask; for example:
-e INST_RETIRED_ANY_P:100000:0:1:0
^ ^ ^ ^
| | | |--- '0': do not record
user space samples
| | |-- '1': record kernel space
samples
| |-- '0': the null unit mask
|--count value
Event names for some IBM PowerPC systems include a _GRP<n>
(group number) suffix. You can pass either the full event name
or the base event name (i.e., without the suffix) to operf.
If the base event name is passed, operf will automatically
choose an appropriate group number suffix for the event; thus,
OProfile post-processing tools will always show real event
names that include the group number suffix. When no event
specification is given, the default event for the running
processor type will be used for profiling. Use ophelp to list
the available events for your processor type.
--callgraph / -g
This option enables the callgraph to be saved during
profiling. NOTE: The full callchain is recorded, so there is
no depth limit.
--separate-thread / -t
This option categorizes samples by thread group ID (tgid) and
thread ID (tid). The '--separate-thread' option is useful for
seeing per-thread samples in multi-threaded applications.
When used in conjunction with the '--system-wide' option, the
'--separate-thread' option is also useful for seeing per-
process (i.e., per-thread group) samples for the case where
multiple processes are executing the same program during a
profiling run.
--separate-cpu / -c
This option categorizes samples by cpu.
--session-dir / -d path
This option specifies the session path to hold the sample
data. If not specified, the data is saved in the oprofile_data
directory on the current path.
--lazy-conversion / -l
Use this option to reduce the overhead of operf during
profiling. Normally, profile data received from the kernel is
converted to OProfile format during profiling time. This is
typically not an issue when profiling a single application.
But when using the --system-wide option, this on-the-fly
conversion process can cause noticeable overhead, particularly
on busy multi-processor systems. The --lazy-conversion option
directs operf to wait until profiling is completed to do the
conversion of profile data.
Note: This option is not recommended to be used in conjunction
with the --pid option for profiling multi-threaded processes.
Depending on the order of thread creation (or forking of new
processes), you may not get any samples for the new
threads/processes.
--append / -a
By default, operf moves old profile data from
<session_dir>/samples/current to
<session_dir>/samples/previous. If a 'previous' profile
already existed, it will be replaced. If the --append option
is passed, old profile data is left in place and new profile
data will be added to it, and the 'previous' profile (if one
existed) will remain untouched. To access the 'previous'
profile, simply add a session specification to the normal
invocation of oprofile post-processing tools. For example:
opreport session:previous
--verbose / -V level
A comma-separated list of debugging control values, used to
increase the verbosity of the output. Valid values are:
debug, record, convert, misc, sfile, arcs, or the special
value, 'all'.
--version / -v
Show operf version.
--help / -h
Display brief usage message.
--usage / -u
Display brief usage message.
$ operf make
This man page is current for oprofile-1.2.0git.
opreport(1), opannotate(1).
This page is part of the oprofile (a system-wide profiler for Linux)
project. Information about the project can be found at
⟨http://oprofile.sourceforge.net/news/⟩. If you have a bug report for
this manual page, see ⟨http://oprofile.sourceforge.net/bugs/⟩. This
page was obtained from the project's upstream Git repository ⟨git⟩ on
2017-07-05. If you discover any rendering problems in this HTML ver‐
sion 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 man‐
ual page), send a mail to man-pages@man7.org
oprofile 1.2.0git Wed 05 July 2017 OPERF(1)