Re: Problem with (Saturn) Profiler
Re: Problem with (Saturn) Profiler
- Subject: Re: Problem with (Saturn) Profiler
- From: Dieter Oberkofler <email@hidden>
- Date: Thu, 29 Jan 2009 21:20:42 +0100
On 29.01.2009, at 21:17, Rick Altherr wrote:
On Jan 29, 2009, at 12:11 PM, Dieter Oberkofler wrote:
On 29.01.2009, at 21:04, Rick Altherr wrote:
On Jan 29, 2009, at 11:38 AM, Dieter Oberkofler wrote:
On 26.01.2009, at 17:58, Rick Altherr wrote:
On Jan 25, 2009, at 8:56 AM, Dieter Oberkofler wrote:
I have been trying to profile a i386 application and ended up
in using Saturn as "the" only traditional (each function is
actually reported) profiler according to the documentation.
After quite a few hours of recompiling, linking and guessing
(it seems as if when running an application bundle in Saturn,
the LSEnvironment is not evaluated) I finally have a fully
instrumented application that can be executed in Saturn. This
is what I did and I after my run, I wanted to load the
generated Saturn data file and end up with the following error
message: "The document "..." could not be opened. The file is
to large". Checking the file shows that the fine is less then
2GB. A few questions that might help:
1) Is Saturn the proper tool to do some simple function
profiling?
That all depends on what type of "simple function profiling" you
want to do. Saturn is an exact function tracer meaning it has
high overheard and knows the precise duration of every function
call on every thread. It requires recompilation of your program
and will cause your program to run at less than half its non-
instrumented speed.
If you don't need to know precise information, you want to use
Shark's Time Profile. It provides a statistical sampling of
your programs execution. It can't tell you the amount of
execution time for every function in your program or how often
it is called, but it can tell you what portions of your program
are taking the most execution time. It has very low overhead
(less than 1% typically) and requires no modifications to your
program.
I had a look at Shark but this would not help. I need am exact
timing of each function and this seems only to be possible with
Saturn.
Is there a specific reason you need exact function timing of
_every_ function in a given code path? Most of the time you don't
need that and can answer questions related to performance by a
combination statistical sampling and tracing specific functions.
No, I would only need to trace a a range of function but this seems
not be possible as a restriction with the frond-end. Should it be?
This is not available in the front-end as you need to place the
start/stopSaturn() calls in your application.
I have now tried to use the API (initSaturn, startSaturn,
stopSaturn) but got stuck as well:
How can I prevent the Saturn front-end to start profiling by
default and only begin when I use startSaturn?
Don't use the front-end to launch the app. If you are using start/
stopSaturn(), you can just run the instrumented program normally
and it will generate the Saturn profile file.
Can I also run a bundle app?
libSaturn can be used by any executable as long as initSaturn is
called first, and start/stopSaturn() are called in pairs.
Does initSaturn automatically start profiling?
Can I start the bundle or do I have to start the binary within the
bundle?
Would I get an error if start/stop is not called in pairs?
--
Rick Altherr
Architecture and Performance Group
email@hidden
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