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NAME | SYNOPSIS | DESCRIPTION | RUN MODES | OTHER OPTIONS | EXAMPLE | VERSION | SEE ALSO | COLOPHON |
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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-1.5.0git.
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://git.code.sf.net/p/oprofile/oprofile⟩ on 2024-06-14. (At
that time, the date of the most recent commit that was found in
the repository was 2021-11-29.) 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
[email protected]
oprofile 1.5.0git Fri 14 June 2024 OPERF(1)
Pages that refer to this page: ocount(1)
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HTML rendering created 2024-06-26 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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