Re: [Caml-list] an OCaml program profile

[Francois Berenger <berenger@riken.jp>]

For the record, I replaced a function using a list
and a hash table by a function using a float array.
Since the culprit function is a numerical algorithm,
that's probably what I should have done from the beginning.
The program is way faster now.

On 09/06/2013 05:49 PM, Gabriel Scherer wrote:
> I have found the "poor man profiler" approach to work well when you
> want to know not only which functions calls some slow runtime function
> the most, but only in which situation (it depends on the callstack and
> not only the source location). Ygrek's pmpa script is very helpful for
> that
>    http://ygrek.org.ua/p/code/pmpa
>
>
> On Fri, Sep 6, 2013 at 10:28 AM, John Whitington
> <john@coherentgraphics.co.uk> wrote:
>> Hi,
>>
>>
>> Francois Berenger wrote:
>>>
>>> Hello,
>>>
>>> I am running experiments with a program.
>>> I'd like the program to run faster because
>>> it would reduce experiments round-trip.
>>>
>>> Here is the top of the profile:
>>> ---
>>> Flat profile:
>>>
>>> Each sample counts as 0.01 seconds.
>>> % cumulative self self total
>>> time seconds seconds calls s/call s/call name
>>> 58.07 132.13 132.13 161527987 0.00 0.00 caml_fl_allocate
>>> 21.13 180.21 48.08 2339 0.02 0.02 caml_fl_add_blocks
>>> 4.87 191.30 11.09 5497 0.00 0.00 mark_slice
>>> 1.65 195.06 3.76 979591485 0.00 0.00 caml_page_table_lookup
>>> 1.50 198.47 3.41 5620 0.00 0.00 sweep_slice
>>> 1.20 201.21 2.74 186584504 0.00 0.00 caml_oldify_one
>>> 1.04 203.57 2.36 134849325 0.00 0.00 compare_val
>>> 1.02 205.89 2.32 290049921 0.00 0.00 caml_float_compare
>>> 0.80 207.71 1.82 123048730 0.00 0.00 caml_hash
>>> 0.76 209.44 1.73 161525648 0.00 0.00 caml_alloc_shr
>>> ---
>>>
>>> I think the program spends most of its time doing garbage
>>> collection.
>>>
>>> How can I make it go faster?
>>
>>
>> Look further down the profile in the individual numbered sections for each
>> function. The section for "caml_call_gc" usually provides the most useful
>> start.
>>
>> For example, if most calls to caml_call_gc are from List.rev, look at calls
>> to that etc. It's not entirely straightforward, but after a bit of following
>> numbers around the file, you'll get used to it.
>>
>> Thanks,
>>
>> --
>> John Whitington
>> Director, Coherent Graphics Ltd
>> http://www.coherentpdf.com/
>>
>>
>>
>> --
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>