+++ /dev/null
-perf-trace-perl(1)
-==================
-
-NAME
-----
-perf-trace-perl - Process trace data with a Perl script
-
-SYNOPSIS
---------
-[verse]
-'perf trace' [-s [Perl]:script[.pl] ]
-
-DESCRIPTION
------------
-
-This perf trace option is used to process perf trace data using perf's
-built-in Perl interpreter. It reads and processes the input file and
-displays the results of the trace analysis implemented in the given
-Perl script, if any.
-
-STARTER SCRIPTS
----------------
-
-You can avoid reading the rest of this document by running 'perf trace
--g perl' in the same directory as an existing perf.data trace file.
-That will generate a starter script containing a handler for each of
-the event types in the trace file; it simply prints every available
-field for each event in the trace file.
-
-You can also look at the existing scripts in
-~/libexec/perf-core/scripts/perl for typical examples showing how to
-do basic things like aggregate event data, print results, etc. Also,
-the check-perf-trace.pl script, while not interesting for its results,
-attempts to exercise all of the main scripting features.
-
-EVENT HANDLERS
---------------
-
-When perf trace is invoked using a trace script, a user-defined
-'handler function' is called for each event in the trace. If there's
-no handler function defined for a given event type, the event is
-ignored (or passed to a 'trace_handled' function, see below) and the
-next event is processed.
-
-Most of the event's field values are passed as arguments to the
-handler function; some of the less common ones aren't - those are
-available as calls back into the perf executable (see below).
-
-As an example, the following perf record command can be used to record
-all sched_wakeup events in the system:
-
- # perf record -a -e sched:sched_wakeup
-
-Traces meant to be processed using a script should be recorded with
-the above option: -a to enable system-wide collection.
-
-The format file for the sched_wakep event defines the following fields
-(see /sys/kernel/debug/tracing/events/sched/sched_wakeup/format):
-
-----
- format:
- field:unsigned short common_type;
- field:unsigned char common_flags;
- field:unsigned char common_preempt_count;
- field:int common_pid;
- field:int common_lock_depth;
-
- field:char comm[TASK_COMM_LEN];
- field:pid_t pid;
- field:int prio;
- field:int success;
- field:int target_cpu;
-----
-
-The handler function for this event would be defined as:
-
-----
-sub sched::sched_wakeup
-{
- my ($event_name, $context, $common_cpu, $common_secs,
- $common_nsecs, $common_pid, $common_comm,
- $comm, $pid, $prio, $success, $target_cpu) = @_;
-}
-----
-
-The handler function takes the form subsystem::event_name.
-
-The $common_* arguments in the handler's argument list are the set of
-arguments passed to all event handlers; some of the fields correspond
-to the common_* fields in the format file, but some are synthesized,
-and some of the common_* fields aren't common enough to to be passed
-to every event as arguments but are available as library functions.
-
-Here's a brief description of each of the invariant event args:
-
- $event_name the name of the event as text
- $context an opaque 'cookie' used in calls back into perf
- $common_cpu the cpu the event occurred on
- $common_secs the secs portion of the event timestamp
- $common_nsecs the nsecs portion of the event timestamp
- $common_pid the pid of the current task
- $common_comm the name of the current process
-
-All of the remaining fields in the event's format file have
-counterparts as handler function arguments of the same name, as can be
-seen in the example above.
-
-The above provides the basics needed to directly access every field of
-every event in a trace, which covers 90% of what you need to know to
-write a useful trace script. The sections below cover the rest.
-
-SCRIPT LAYOUT
--------------
-
-Every perf trace Perl script should start by setting up a Perl module
-search path and 'use'ing a few support modules (see module
-descriptions below):
-
-----
- use lib "$ENV{'PERF_EXEC_PATH'}/scripts/perl/Perf-Trace-Util/lib";
- use lib "./Perf-Trace-Util/lib";
- use Perf::Trace::Core;
- use Perf::Trace::Context;
- use Perf::Trace::Util;
-----
-
-The rest of the script can contain handler functions and support
-functions in any order.
-
-Aside from the event handler functions discussed above, every script
-can implement a set of optional functions:
-
-*trace_begin*, if defined, is called before any event is processed and
-gives scripts a chance to do setup tasks:
-
-----
- sub trace_begin
- {
- }
-----
-
-*trace_end*, if defined, is called after all events have been
- processed and gives scripts a chance to do end-of-script tasks, such
- as display results:
-
-----
-sub trace_end
-{
-}
-----
-
-*trace_unhandled*, if defined, is called after for any event that
- doesn't have a handler explicitly defined for it. The standard set
- of common arguments are passed into it:
-
-----
-sub trace_unhandled
-{
- my ($event_name, $context, $common_cpu, $common_secs,
- $common_nsecs, $common_pid, $common_comm) = @_;
-}
-----
-
-The remaining sections provide descriptions of each of the available
-built-in perf trace Perl modules and their associated functions.
-
-AVAILABLE MODULES AND FUNCTIONS
--------------------------------
-
-The following sections describe the functions and variables available
-via the various Perf::Trace::* Perl modules. To use the functions and
-variables from the given module, add the corresponding 'use
-Perf::Trace::XXX' line to your perf trace script.
-
-Perf::Trace::Core Module
-~~~~~~~~~~~~~~~~~~~~~~~~
-
-These functions provide some essential functions to user scripts.
-
-The *flag_str* and *symbol_str* functions provide human-readable
-strings for flag and symbolic fields. These correspond to the strings
-and values parsed from the 'print fmt' fields of the event format
-files:
-
- flag_str($event_name, $field_name, $field_value) - returns the string represention corresponding to $field_value for the flag field $field_name of event $event_name
- symbol_str($event_name, $field_name, $field_value) - returns the string represention corresponding to $field_value for the symbolic field $field_name of event $event_name
-
-Perf::Trace::Context Module
-~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-Some of the 'common' fields in the event format file aren't all that
-common, but need to be made accessible to user scripts nonetheless.
-
-Perf::Trace::Context defines a set of functions that can be used to
-access this data in the context of the current event. Each of these
-functions expects a $context variable, which is the same as the
-$context variable passed into every event handler as the second
-argument.
-
- common_pc($context) - returns common_preempt count for the current event
- common_flags($context) - returns common_flags for the current event
- common_lock_depth($context) - returns common_lock_depth for the current event
-
-Perf::Trace::Util Module
-~~~~~~~~~~~~~~~~~~~~~~~~
-
-Various utility functions for use with perf trace:
-
- nsecs($secs, $nsecs) - returns total nsecs given secs/nsecs pair
- nsecs_secs($nsecs) - returns whole secs portion given nsecs
- nsecs_nsecs($nsecs) - returns nsecs remainder given nsecs
- nsecs_str($nsecs) - returns printable string in the form secs.nsecs
- avg($total, $n) - returns average given a sum and a total number of values
-
-SEE ALSO
---------
-linkperf:perf-trace[1]
projects / mv-sheeva.git / blobdiff