operf(1) — Linux manual page


OPERF(1)                 General Commands Manual                OPERF(1)

NAME         top

       operf - Performance profiler tool for Linux

SYNOPSIS         top

       operf [ options ] [ --system-wide | --pid <pid> | [ command [
       args ] ] ]

DESCRIPTION         top

       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

       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.

RUN MODES         top

       One (and only one) of the following run modes must be specified:

              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.

OTHER OPTIONS         top

       --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

              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

              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

              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
                                       |--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

              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

       --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

              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.

EXAMPLE         top

       $ operf make

VERSION         top

       This man page is current for oprofile-1.5.0git.

SEE ALSO         top

       opreport(1), opannotate(1).

COLOPHON         top

       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 2023-12-22.  (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

oprofile 1.5.0git         Fri 22 December 2023                  OPERF(1)

Pages that refer to this page: ocount(1)