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From: Juliette Salexa on 16 Jun 2010 13:21
Hello,

In this tutorial:
http://www.mathworks.com/company/newsletters/news_notes/may03/images/profiler2_large.jpg

It shows 4 columns titled "time" "calls" "accel" and "line"

I'm wondering why my profiler doens't show the 'accel' column ?

I have Matlab 2010a and all the toolboxes.

It's hard for me to find out what I'm missing because when I google "matlab JIT" ,
almost every page is external to mathworks, and the top 2 results are from 2003 and before.

Does anyone know how I can get that column to display ?

Thanks.
From: Steven Lord on 17 Jun 2010 11:05

"Juliette Salexa" <juliette.physicist(a)gmail.com> wrote in message
news:hvb160$368$1(a)fred.mathworks.com...
> Hello,
>
> In this tutorial:
> http://www.mathworks.com/company/newsletters/news_notes/may03/images/profiler2_large.jpg
>
> It shows 4 columns titled "time" "calls" "accel" and "line"
>
> I'm wondering why my profiler doens't show the 'accel' column ?

Because that column was specifically removed from the Profiler view a few
years ago. The Profiler was intended to answer the question "How long does
my code take to run" -- ideally you shouldn't _care_ whether or not a
particular line or section of your code was accelerated.

--
Steve Lord
slord(a)mathworks.com
comp.soft-sys.matlab (CSSM) FAQ: http://matlabwiki.mathworks.com/MATLAB_FAQ
To contact Technical Support use the Contact Us link on
http://www.mathworks.com


From: Juliette Salexa on 18 Jun 2010 10:36
Thanks Steven,

I got that image from:

http://www.mathworks.com/company/newsletters/news_notes/may03/profiler.html

where it says:

"A dot (.) in the acc column means the line accelerated; an x means that it did not. Clicking on the x shows why that line did not accelerate. For example:
Reference to 'i' in a script cannot be accelerated unless 'i' is a defined variable. To apply the builtin 'i', use the notation '1i'."

That piece of advice as to why that line can't be accelerated seems to be quite useful, especially since that message doesn't show up in the MLint warnings.

Is there a way to see messages like this so that we can maximize the amount of acceleration that the JIT compiler can do ?
From: Steven Lord on 18 Jun 2010 10:57

"Juliette Salexa" <juliette.physicist(a)gmail.com> wrote in message
news:hvg08i$250$1(a)fred.mathworks.com...
> Thanks Steven,
>
> I got that image from:
>
> http://www.mathworks.com/company/newsletters/news_notes/may03/profiler.html

Yes -- note that the URL indicates that article is from May 2003, over seven
years ago. Things have changed a bit since then.

> where it says:
>
> "A dot (.) in the acc column means the line accelerated; an x means that
> it did not. Clicking on the x shows why that line did not accelerate. For
> example:
> Reference to 'i' in a script cannot be accelerated unless 'i' is a defined
> variable. To apply the builtin 'i', use the notation '1i'."
>
> That piece of advice as to why that line can't be accelerated seems to be
> quite useful, especially since that message doesn't show up in the MLint
> warnings.
>
> Is there a way to see messages like this so that we can maximize the
> amount of acceleration that the JIT compiler can do ?

NO. I agree with Sarah Zaranek's comment (comment 13) in this posting on
Loren's blog:

http://blogs.mathworks.com/loren/2008/06/25/speeding-up-matlab-applications/


"We recommend not writing specifically for the JIT since the JIT is
constantly evolving. You should though keep in mind the general good
MATLAB-coding practices, such as those listed above."


If you find a piece of code that you think is not performing as well as it
should be, and you can't figure out how to make it faster, contact Technical
Support and/or post it to the newsgroup. They can help you make it faster,
find an alternative approach, or (if you contact Support) enter an
enhancement request into the enhancement database to investigate how to make
it faster.

--
Steve Lord
slord(a)mathworks.com
comp.soft-sys.matlab (CSSM) FAQ: http://matlabwiki.mathworks.com/MATLAB_FAQ
To contact Technical Support use the Contact Us link on
http://www.mathworks.com


From: dpb on 18 Jun 2010 11:01
Steven Lord wrote:
....

> NO. I agree with Sarah Zaranek's comment ...
> "We recommend not writing specifically for the JIT since the JIT is
> constantly evolving. You should though keep in mind the general good
> MATLAB-coding practices, such as those listed above."
>
....

OTOH, isn't it highly likely that if something is discernible as being
bad for JIT now, it's unlikely that practice will become good in the
future???

I can't imagine the kinds of recommendations made at that level are
being changed _that_ rapidly (or conflict that much in advice)...

Additions I can see, certainly.

$0.02, etc., ...

--
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