mirror of https://github.com/odrling/Aegisub
366 lines
13 KiB
HTML
366 lines
13 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
|
|
<html>
|
|
<head>
|
|
<title>Profiler</title>
|
|
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
|
|
<meta name="Author" content="Mike Pall">
|
|
<meta name="Copyright" content="Copyright (C) 2005-2017, Mike Pall">
|
|
<meta name="Language" content="en">
|
|
<link rel="stylesheet" type="text/css" href="bluequad.css" media="screen">
|
|
<link rel="stylesheet" type="text/css" href="bluequad-print.css" media="print">
|
|
</head>
|
|
<body>
|
|
<div id="site">
|
|
<a href="http://luajit.org"><span>Lua<span id="logo">JIT</span></span></a>
|
|
</div>
|
|
<div id="head">
|
|
<h1>Profiler</h1>
|
|
</div>
|
|
<div id="nav">
|
|
<ul><li>
|
|
<a href="luajit.html">LuaJIT</a>
|
|
<ul><li>
|
|
<a href="http://luajit.org/download.html">Download <span class="ext">»</span></a>
|
|
</li><li>
|
|
<a href="install.html">Installation</a>
|
|
</li><li>
|
|
<a href="running.html">Running</a>
|
|
</li></ul>
|
|
</li><li>
|
|
<a href="extensions.html">Extensions</a>
|
|
<ul><li>
|
|
<a href="ext_ffi.html">FFI Library</a>
|
|
<ul><li>
|
|
<a href="ext_ffi_tutorial.html">FFI Tutorial</a>
|
|
</li><li>
|
|
<a href="ext_ffi_api.html">ffi.* API</a>
|
|
</li><li>
|
|
<a href="ext_ffi_semantics.html">FFI Semantics</a>
|
|
</li></ul>
|
|
</li><li>
|
|
<a href="ext_jit.html">jit.* Library</a>
|
|
</li><li>
|
|
<a href="ext_c_api.html">Lua/C API</a>
|
|
</li><li>
|
|
<a class="current" href="ext_profiler.html">Profiler</a>
|
|
</li></ul>
|
|
</li><li>
|
|
<a href="status.html">Status</a>
|
|
<ul><li>
|
|
<a href="changes.html">Changes</a>
|
|
</li></ul>
|
|
</li><li>
|
|
<a href="faq.html">FAQ</a>
|
|
</li><li>
|
|
<a href="http://luajit.org/performance.html">Performance <span class="ext">»</span></a>
|
|
</li><li>
|
|
<a href="http://wiki.luajit.org/">Wiki <span class="ext">»</span></a>
|
|
</li><li>
|
|
<a href="http://luajit.org/list.html">Mailing List <span class="ext">»</span></a>
|
|
</li></ul>
|
|
</div>
|
|
<div id="main">
|
|
<p>
|
|
LuaJIT has an integrated statistical profiler with very low overhead. It
|
|
allows sampling the currently executing stack and other parameters in
|
|
regular intervals.
|
|
</p>
|
|
<p>
|
|
The integrated profiler can be accessed from three levels:
|
|
</p>
|
|
<ul>
|
|
<li>The <a href="#hl_profiler">bundled high-level profiler</a>, invoked by the
|
|
<a href="#j_p"><tt>-jp</tt></a> command line option.</li>
|
|
<li>A <a href="#ll_lua_api">low-level Lua API</a> to control the profiler.</li>
|
|
<li>A <a href="#ll_c_api">low-level C API</a> to control the profiler.</li>
|
|
</ul>
|
|
|
|
<h2 id="hl_profiler">High-Level Profiler</h2>
|
|
<p>
|
|
The bundled high-level profiler offers basic profiling functionality. It
|
|
generates simple textual summaries or source code annotations. It can be
|
|
accessed with the <a href="#j_p"><tt>-jp</tt></a> command line option
|
|
or from Lua code by loading the underlying <tt>jit.p</tt> module.
|
|
</p>
|
|
<p>
|
|
To cut to the chase — run this to get a CPU usage profile by
|
|
function name:
|
|
</p>
|
|
<pre class="code">
|
|
luajit -jp myapp.lua
|
|
</pre>
|
|
<p>
|
|
It's <em>not</em> a stated goal of the bundled profiler to add every
|
|
possible option or to cater for special profiling needs. The low-level
|
|
profiler APIs are documented below. They may be used by third-party
|
|
authors to implement advanced functionality, e.g. IDE integration or
|
|
graphical profilers.
|
|
</p>
|
|
<p>
|
|
Note: Sampling works for both interpreted and JIT-compiled code. The
|
|
results for JIT-compiled code may sometimes be surprising. LuaJIT
|
|
heavily optimizes and inlines Lua code — there's no simple
|
|
one-to-one correspondence between source code lines and the sampled
|
|
machine code.
|
|
</p>
|
|
|
|
<h3 id="j_p"><tt>-jp=[options[,output]]</tt></h3>
|
|
<p>
|
|
The <tt>-jp</tt> command line option starts the high-level profiler.
|
|
When the application run by the command line terminates, the profiler
|
|
stops and writes the results to <tt>stdout</tt> or to the specified
|
|
<tt>output</tt> file.
|
|
</p>
|
|
<p>
|
|
The <tt>options</tt> argument specifies how the profiling is to be
|
|
performed:
|
|
</p>
|
|
<ul>
|
|
<li><tt>f</tt> — Stack dump: function name, otherwise module:line.
|
|
This is the default mode.</li>
|
|
<li><tt>F</tt> — Stack dump: ditto, but dump module:name.</li>
|
|
<li><tt>l</tt> — Stack dump: module:line.</li>
|
|
<li><tt><number></tt> — stack dump depth (callee ←
|
|
caller). Default: 1.</li>
|
|
<li><tt>-<number></tt> — Inverse stack dump depth (caller
|
|
→ callee).</li>
|
|
<li><tt>s</tt> — Split stack dump after first stack level. Implies
|
|
depth ≥ 2 or depth ≤ -2.</li>
|
|
<li><tt>p</tt> — Show full path for module names.</li>
|
|
<li><tt>v</tt> — Show VM states.</li>
|
|
<li><tt>z</tt> — Show <a href="#jit_zone">zones</a>.</li>
|
|
<li><tt>r</tt> — Show raw sample counts. Default: show percentages.</li>
|
|
<li><tt>a</tt> — Annotate excerpts from source code files.</li>
|
|
<li><tt>A</tt> — Annotate complete source code files.</li>
|
|
<li><tt>G</tt> — Produce raw output suitable for graphical tools.</li>
|
|
<li><tt>m<number></tt> — Minimum sample percentage to be shown.
|
|
Default: 3%.</li>
|
|
<li><tt>i<number></tt> — Sampling interval in milliseconds.
|
|
Default: 10ms.<br>
|
|
Note: The actual sampling precision is OS-dependent.</li>
|
|
</ul>
|
|
<p>
|
|
The default output for <tt>-jp</tt> is a list of the most CPU consuming
|
|
spots in the application. Increasing the stack dump depth with (say)
|
|
<tt>-jp=2</tt> may help to point out the main callers or callees of
|
|
hotspots. But sample aggregation is still flat per unique stack dump.
|
|
</p>
|
|
<p>
|
|
To get a two-level view (split view) of callers/callees, use
|
|
<tt>-jp=s</tt> or <tt>-jp=-s</tt>. The percentages shown for the second
|
|
level are relative to the first level.
|
|
</p>
|
|
<p>
|
|
To see how much time is spent in each line relative to a function, use
|
|
<tt>-jp=fl</tt>.
|
|
</p>
|
|
<p>
|
|
To see how much time is spent in different VM states or
|
|
<a href="#jit_zone">zones</a>, use <tt>-jp=v</tt> or <tt>-jp=z</tt>.
|
|
</p>
|
|
<p>
|
|
Combinations of <tt>v/z</tt> with <tt>f/F/l</tt> produce two-level
|
|
views, e.g. <tt>-jp=vf</tt> or <tt>-jp=fv</tt>. This shows the time
|
|
spent in a VM state or zone vs. hotspots. This can be used to answer
|
|
questions like "Which time consuming functions are only interpreted?" or
|
|
"What's the garbage collector overhead for a specific function?".
|
|
</p>
|
|
<p>
|
|
Multiple options can be combined — but not all combinations make
|
|
sense, see above. E.g. <tt>-jp=3si4m1</tt> samples three stack levels
|
|
deep in 4ms intervals and shows a split view of the CPU consuming
|
|
functions and their callers with a 1% threshold.
|
|
</p>
|
|
<p>
|
|
Source code annotations produced by <tt>-jp=a</tt> or <tt>-jp=A</tt> are
|
|
always flat and at the line level. Obviously, the source code files need
|
|
to be readable by the profiler script.
|
|
</p>
|
|
<p>
|
|
The high-level profiler can also be started and stopped from Lua code with:
|
|
</p>
|
|
<pre class="code">
|
|
require("jit.p").start(options, output)
|
|
...
|
|
require("jit.p").stop()
|
|
</pre>
|
|
|
|
<h3 id="jit_zone"><tt>jit.zone</tt> — Zones</h3>
|
|
<p>
|
|
Zones can be used to provide information about different parts of an
|
|
application to the high-level profiler. E.g. a game could make use of an
|
|
<tt>"AI"</tt> zone, a <tt>"PHYS"</tt> zone, etc. Zones are hierarchical,
|
|
organized as a stack.
|
|
</p>
|
|
<p>
|
|
The <tt>jit.zone</tt> module needs to be loaded explicitly:
|
|
</p>
|
|
<pre class="code">
|
|
local zone = require("jit.zone")
|
|
</pre>
|
|
<ul>
|
|
<li><tt>zone("name")</tt> pushes a named zone to the zone stack.</li>
|
|
<li><tt>zone()</tt> pops the current zone from the zone stack and
|
|
returns its name.</li>
|
|
<li><tt>zone:get()</tt> returns the current zone name or <tt>nil</tt>.</li>
|
|
<li><tt>zone:flush()</tt> flushes the zone stack.</li>
|
|
</ul>
|
|
<p>
|
|
To show the time spent in each zone use <tt>-jp=z</tt>. To show the time
|
|
spent relative to hotspots use e.g. <tt>-jp=zf</tt> or <tt>-jp=fz</tt>.
|
|
</p>
|
|
|
|
<h2 id="ll_lua_api">Low-level Lua API</h2>
|
|
<p>
|
|
The <tt>jit.profile</tt> module gives access to the low-level API of the
|
|
profiler from Lua code. This module needs to be loaded explicitly:
|
|
<pre class="code">
|
|
local profile = require("jit.profile")
|
|
</pre>
|
|
<p>
|
|
This module can be used to implement your own higher-level profiler.
|
|
A typical profiling run starts the profiler, captures stack dumps in
|
|
the profiler callback, adds them to a hash table to aggregate the number
|
|
of samples, stops the profiler and then analyzes all of the captured
|
|
stack dumps. Other parameters can be sampled in the profiler callback,
|
|
too. But it's important not to spend too much time in the callback,
|
|
since this may skew the statistics.
|
|
</p>
|
|
|
|
<h3 id="profile_start"><tt>profile.start(mode, cb)</tt>
|
|
— Start profiler</h3>
|
|
<p>
|
|
This function starts the profiler. The <tt>mode</tt> argument is a
|
|
string holding options:
|
|
</p>
|
|
<ul>
|
|
<li><tt>f</tt> — Profile with precision down to the function level.</li>
|
|
<li><tt>l</tt> — Profile with precision down to the line level.</li>
|
|
<li><tt>i<number></tt> — Sampling interval in milliseconds (default
|
|
10ms).</br>
|
|
Note: The actual sampling precision is OS-dependent.
|
|
</li>
|
|
</ul>
|
|
<p>
|
|
The <tt>cb</tt> argument is a callback function which is called with
|
|
three arguments: <tt>(thread, samples, vmstate)</tt>. The callback is
|
|
called on a separate coroutine, the <tt>thread</tt> argument is the
|
|
state that holds the stack to sample for profiling. Note: do
|
|
<em>not</em> modify the stack of that state or call functions on it.
|
|
</p>
|
|
<p>
|
|
<tt>samples</tt> gives the number of accumulated samples since the last
|
|
callback (usually 1).
|
|
</p>
|
|
<p>
|
|
<tt>vmstate</tt> holds the VM state at the time the profiling timer
|
|
triggered. This may or may not correspond to the state of the VM when
|
|
the profiling callback is called. The state is either <tt>'N'</tt>
|
|
native (compiled) code, <tt>'I'</tt> interpreted code, <tt>'C'</tt>
|
|
C code, <tt>'G'</tt> the garbage collector, or <tt>'J'</tt> the JIT
|
|
compiler.
|
|
</p>
|
|
|
|
<h3 id="profile_stop"><tt>profile.stop()</tt>
|
|
— Stop profiler</h3>
|
|
<p>
|
|
This function stops the profiler.
|
|
</p>
|
|
|
|
<h3 id="profile_dump"><tt>dump = profile.dumpstack([thread,] fmt, depth)</tt>
|
|
— Dump stack </h3>
|
|
<p>
|
|
This function allows taking stack dumps in an efficient manner. It
|
|
returns a string with a stack dump for the <tt>thread</tt> (coroutine),
|
|
formatted according to the <tt>fmt</tt> argument:
|
|
</p>
|
|
<ul>
|
|
<li><tt>p</tt> — Preserve the full path for module names. Otherwise
|
|
only the file name is used.</li>
|
|
<li><tt>f</tt> — Dump the function name if it can be derived. Otherwise
|
|
use module:line.</li>
|
|
<li><tt>F</tt> — Ditto, but dump module:name.</li>
|
|
<li><tt>l</tt> — Dump module:line.</li>
|
|
<li><tt>Z</tt> — Zap the following characters for the last dumped
|
|
frame.</li>
|
|
<li>All other characters are added verbatim to the output string.</li>
|
|
</ul>
|
|
<p>
|
|
The <tt>depth</tt> argument gives the number of frames to dump, starting
|
|
at the topmost frame of the thread. A negative number dumps the frames in
|
|
inverse order.
|
|
</p>
|
|
<p>
|
|
The first example prints a list of the current module names and line
|
|
numbers of up to 10 frames in separate lines. The second example prints
|
|
semicolon-separated function names for all frames (up to 100) in inverse
|
|
order:
|
|
</p>
|
|
<pre class="code">
|
|
print(profile.dumpstack(thread, "l\n", 10))
|
|
print(profile.dumpstack(thread, "lZ;", -100))
|
|
</pre>
|
|
|
|
<h2 id="ll_c_api">Low-level C API</h2>
|
|
<p>
|
|
The profiler can be controlled directly from C code, e.g. for
|
|
use by IDEs. The declarations are in <tt>"luajit.h"</tt> (see
|
|
<a href="ext_c_api.html">Lua/C API</a> extensions).
|
|
</p>
|
|
|
|
<h3 id="luaJIT_profile_start"><tt>luaJIT_profile_start(L, mode, cb, data)</tt>
|
|
— Start profiler</h3>
|
|
<p>
|
|
This function starts the profiler. <a href="#profile_start">See
|
|
above</a> for a description of the <tt>mode</tt> argument.
|
|
</p>
|
|
<p>
|
|
The <tt>cb</tt> argument is a callback function with the following
|
|
declaration:
|
|
</p>
|
|
<pre class="code">
|
|
typedef void (*luaJIT_profile_callback)(void *data, lua_State *L,
|
|
int samples, int vmstate);
|
|
</pre>
|
|
<p>
|
|
<tt>data</tt> is available for use by the callback. <tt>L</tt> is the
|
|
state that holds the stack to sample for profiling. Note: do
|
|
<em>not</em> modify this stack or call functions on this stack —
|
|
use a separate coroutine for this purpose. <a href="#profile_start">See
|
|
above</a> for a description of <tt>samples</tt> and <tt>vmstate</tt>.
|
|
</p>
|
|
|
|
<h3 id="luaJIT_profile_stop"><tt>luaJIT_profile_stop(L)</tt>
|
|
— Stop profiler</h3>
|
|
<p>
|
|
This function stops the profiler.
|
|
</p>
|
|
|
|
<h3 id="luaJIT_profile_dumpstack"><tt>p = luaJIT_profile_dumpstack(L, fmt, depth, len)</tt>
|
|
— Dump stack </h3>
|
|
<p>
|
|
This function allows taking stack dumps in an efficient manner.
|
|
<a href="#profile_dump">See above</a> for a description of <tt>fmt</tt>
|
|
and <tt>depth</tt>.
|
|
</p>
|
|
<p>
|
|
This function returns a <tt>const char *</tt> pointing to a
|
|
private string buffer of the profiler. The <tt>int *len</tt>
|
|
argument returns the length of the output string. The buffer is
|
|
overwritten on the next call and deallocated when the profiler stops.
|
|
You either need to consume the content immediately or copy it for later
|
|
use.
|
|
</p>
|
|
<br class="flush">
|
|
</div>
|
|
<div id="foot">
|
|
<hr class="hide">
|
|
Copyright © 2005-2017 Mike Pall
|
|
<span class="noprint">
|
|
·
|
|
<a href="contact.html">Contact</a>
|
|
</span>
|
|
</div>
|
|
</body>
|
|
</html>
|