
LuaJIT 2.1 Profiler released - qwertzlcoatl
http://permalink.gmane.org/gmane.comp.lang.lua.luajit/3413
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camperman
LuaJIT is a work of great beauty and efficiency. I've been working on a
commercial product for small ARM boards where rapid prototyping has been
essential because of ever changing requirements but the speed of the finished
code is also paramount. LuaJIT has made this project an absolute pleasure. It
wraps C libraries cleanly, it runs within 5-10% of native code speed on the
ARM (I checked because I didn't believe it at first) and it's 100% compatible
with all the Lua 5.1 supporting libraries I need. This new profiler will be a
great addition to the toolbox along with ZeroBrane Studio's debugger which I
just discovered this week and which also rocks.

Mike Pall needs several Jolt Awards.

~~~
saosebastiao
That is no lie. I like lua, but it never seemed to be the best fit for the
problems that I need to solve. Nevertheless, if I could pick any one person to
work on my language/runtimes of choice, it would be Mike Pall.

Now does Mike have any kids? Start pointing them in the direction of Rust, por
favor :)

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acqq
The most interesting conclusions of Mike Pall reflect my experiences: sampling
profilers are often much more usable in practice than instrumentation:

 _As you might have noticed, I had to change my plans compared to the original
approach presented in June. The main problem with the instrumenting profiler
was finding high-precision and high-speed timing sources for all platforms._
(...) _The necessary pipeline flushes shadowed the actual timings up to the
point where the measurements were less accurate than with a sampling profiler!
Other platforms offered only inaccurate timing sources or none that are
accessible from user mode. And to top it off, the instrumentation added
considerable overhead._ (...) _I had to scrap that work and decided to go with
a sampling profiler._

And I don't know any other scripting language with a built-in sampling
profiler. Does anybody?

~~~
illumen
python

~~~
StefanKarpinski
Python doesn't have a built-in profiler – it has various add-on profilers [1].

[1]
[http://docs.python.org/3/library/profile.html](http://docs.python.org/3/library/profile.html)

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copx
Great news, up until now there was no good Lua profiler.

You can thank GIANTS Software for this one:
[http://luajit.org/sponsors.html](http://luajit.org/sponsors.html)

 _GIANTS Software GmbH is sponsoring the development of a low-overhead
profiling functionality for LuaJIT 2.1, starting in June 2013. GIANTS Software
develops a variety of simulation games for desktop, mobile and consoles. These
games make extensive use of Lua for scripting and modding. Switching to LuaJIT
was instrumental in reducing the CPU load and sustaining the required frame
rates on all platforms.

Existing profilers for Lua and LuaJIT are based on Lua hooks and debug
queries. The use of these generic mechanisms incurs a high overhead. Execution
of a program under control of such a profiler causes substantial slow-downs.
Actual use of the program (gameplay) may be impossible in some cases.

The goal is to design and implement a new profiling functionality that has a
much lower overhead, better control of detail and high flexibility._

~~~
denzquix
It kind of astounds me how many previous sponsors are anonymous. (Well,
sponsored features, I should say. I guess it could be the same one anonymous
sponsor.) I'd be interested to know, just in general terms, what kind of real-
world situation(s) there are where the downside to being public about this is
greater than the goodwill/respect they would get for doing it. Maybe they do
not want to be known as a company willing to sponsor development that they
don't "own"? Could there be legal ramifications?

~~~
mikemike
Most of the sponsors who wished to remain anonymous didn't want their
competition to know they use LuaJIT. :-)

~~~
denzquix
Aha, that makes sense. Well, good luck to them on keeping their "secret"
weapon under wraps :-)

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jnbiche
In this day of multiple megabyte applications, it's amazing to me how much
Mike Pall is able to fit into ~300 kB.

Mike Pall is without doubt one of the most talented developers of our
generation, alongside people like Fabrice Bellard and Jeff Dean (to name a
few).

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rustc
Slightly off-topic, but does anyone know how I can download the complete
mailing list archive data (of luajit)? Many of Mike's posts are very
informative and useful, and I'd like to be able to search/read them easily,
offline.

~~~
zeckalpha
Either use NNTP, or [http://gmane.org/export.php](http://gmane.org/export.php)

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aktau
When I grow up, I want to be Mike Pall.

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otikik
This. Is. Awesome.

