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 /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.

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

              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 /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:

              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
                                       |      |-- '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

       --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-1.4.0git.

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 
       ⟨⟩.  If you have a bug report for
       this manual page, see ⟨⟩.  This
       page was obtained from the project's upstream Git repository ⟨git
       clone git://⟩ on 2020-02-08.  (At
       that time, the date of the most recent commit that was found in the
       repository was 2019-09-24.)  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 1.4.0git           Sat 08 February 2020                    OPERF(1)

Pages that refer to this page: ocount(1)