Re: Ada memory management seems slow

[Martin Krischik <krischik@users.sourceforge.net>]

Makhno wrote:

>> GNAT uses malloc and free from the C library  for memory management - so
>> performace is the same as with C. Only with C nobody measures the
>> performance - people just expect malloc and free to be as fast as
>> possible.
> 
> I find this difficult to believe - I have experience of using free() in C,
> and unless the lists are far bigger than I think they are, C is nowhere
> near as slow as this.

Do you use Ada.Finalization? Ada.Finalization can eat performace when
compared with C. C does not have automatic finalisation.

> Is there any way I can check precisely what Ada is using? The program is
> calling something called FREE which is defined as some sort of deallocator
> called Ada.Unchecked_Deallocation

You can look up the source code. From you installation directory you should
have something like:

.../lib/gcc/x86_64-unknown-linux-gnu/3.4.5/adainclude

Where you find almost the full sources for all gnat library functions. Look
at s-crtl.ads where the actual malloc call is.

>>> I was wondering what options are available for memory management, or
>>> whether I am inadvertently using a 'slow' mode.
>>
>> Well there is indeed a memory debug option - but its off by default.
> 
> I'm using gnatmake with -O3.

In which case GNAT will automaticy inline if possible - using the sources
mentioned above ;-)

Well, I have a cold - maybe someone else can elaborate on finalisation.

Martin

-- 
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Ada programming at: http://ada.krischik.com