Re: [Caml-list] Behaviour of an OCaml program: any possible GC improvement?

[John Whitington <john@coherentgraphics.co.uk>]

Hi David,

David MENTRE wrote:
> Hello,
>
> I'm using OCaml 3.11.2 on Linux (Debian Squeeze 6.0) x86_64 platform.
>
> I have a program that exhibits the following gprof profile. A lot of
> time is spent in the GC (more than 56 %). Is there anything I can do
> with respect to the GC? Otherwise, this program is a typical symbolic
> manipulation program, handling trees made of Sum types and small lists
> of them (1 to 3 elements).

Can you supply the section under "caml_call_gc"? For example:

>                 0.00    0.03       1/4988        camlPdfutil__fun_2922 [136]
>                 0.00    0.03       1/4988        camlPdfutil__takewhile_reverse_inner_1655 [133]
>                 0.00    0.03       1/4988        camlPdfutil__ilist_1873 [135]
>                 0.00    0.03       1/4988        camlPdf__x1_1414 [130]
>                 0.00    0.03       1/4988        camlPdfread__lex_object_at_1344 [132]
>                 0.00    0.03       1/4988        camlPdfread__process_parse_dictionary_1440 [103]
>                 0.00    0.03       1/4988        camlPdfread__parse_dictionary_1451 <cycle 1> [97]
>                 0.00    0.03       1/4988        camlPdfread__parse_to_tree_1473 <cycle 1> [131]
>                 0.00    0.03       1/4988        camlHashtbl__insert_bucket_1068 [129]
>                 0.00    0.07       2/4988        camlPdfwrite__fun_1642 <cycle 1> [110]
>                 0.00    0.07       2/4988        camlPdfread__mkpairs_1442 [112]
>                 0.00    0.07       2/4988        camlPdfread__fun_2689 <cycle 1> [111]
>                 0.00    0.10       3/4988        camlPdfread__lex_name_1217 <cycle 1> [92]
>                 0.00    0.14       4/4988        camlPdf__fun_1934 [98]
>                 0.00    0.14       4/4988        camlHashtbl__replace_1112 [96]
>                 0.00    1.93      56/4988        camlPdfread__lex_string_1230 [32]
>                 0.00    2.93      85/4988        camlPdfwrite__strings_of_pdf_1131 <cycle 1> [24]
>                 0.00    3.79     110/4988        camlPdfread__lex_number_1211 [28]
>                 0.00    5.10     148/4988        camlPdfgenlex__lex_item_1109 [45]
>                 0.00    8.86     257/4988        camlHashtbl__mem_1122 [42]
>                 0.00   13.24     384/4988        camlPdfread__parse_array_1452 <cycle 1> [35]
>                 0.00   13.34     387/4988        camlList__rmap_f_1070 <cycle 1> [34]
>                 0.00   31.34     909/4988        camlPdfread__parse_R_inner_1422 [26]
>                 0.00   40.23    1167/4988        camlList__rev_append_1051 [23]
>                 0.00   50.30    1459/4988        camlPdfread__lex_object_at_1352 <cycle 1> [21]
> [7]     65.5    0.00  171.97    4988         caml_call_gc [7]
>                 0.00  171.97    4988/4988        caml_garbage_collection [8]

This is usually a good starting point.

Thanks,

-- 
John Whitington
Director, Coherent Graphics Ltd
http://www.coherentpdf.com/